John Henry Browne, 67, has been practising law for 43 years. Based in Seattle, Washington, he has defended high-profile mass murderers, including serial killer Ted Bundy, who sowed fear across the US in the 1970s, and Robert Bales, an army sergeant who massacred 16 Afghan civilians in 2011

I've always felt drawn to the underdog. Often government gets things wrong. I've represented a number of innocent people. It's kind of my path. What I'm supposed to do.

Performing is part of the job. It came to me naturally. I did theatre in high school. People say I'm a Shakespearean character, flamboyant. I figured out what that means – it means a lawyer who actually has a personality. You can get a big head easily in this business. I struggle with my ego.

I was raised against the death penalty, but after a woman friend was murdered brutally in 1969, I thought, let me find that guy who killed Debbie and I'll take care of him. It sounds woo-woo, but then she came to me in a dream. She never believed in the death penalty, so I went back to fighting it partly as a tribute to her.

I usually have some emotional engagement with clients, but Ted Bundy was a perfect example of someone born evil. I had no compassion for him. But I did want to save him from the death penalty. He was at times smart and handsome. To sit down and talk to him, you would think he was normal. He acted very well. Totally manipulative.

John Henry Browne: ‘Ted Bundy was a perfect example of someone born evil.’ Photograph: Felix Clay for the Guardian

Ted told me one time that in junior high school he would put white mice into this little corral. He would sit there and figure out which ones he would save and which ones he would kill. It was the same with women. Control was his thing. But Ted did tell me something that showed he was 2% not sociopath. He said, "John, I want to be a good person, I'm just not."

He said the reason I was his lawyer for so long – he was always firing lawyers – was because we were so alike. He would mimic me, wear the same clothes. That creeped me out. But he turned down the plea bargain I got to save his life.

At the same time I was defending Ted, I was defending abused women. That didn't confuse me, but apparently it confused a lot of other people.

Bobby Bales was born good. He was student body president, captain of the football team, took care of a gravely disabled boy. Bobby was a victim of our wars. He'd done four tours, had PTSD, then ended up working for macho special forces that gave him drugs and alcohol. Bobby did something evil, but he wasn't evil, and we – our government and army – needed to take responsibility for him. But they didn't. So I did.

And then I go to Afghanistan and see these little kids – victims and witnesses [of the massacre] – that I want to adopt. I gave one my card. She was on crutches, just adorable, and said: "If you want to go to college in the United States, get in touch and I'll make it happen."

The work is hard to shake off. You start looking at the world through dirty windows. I've been married a number of times and that partly has to do with my job. Living with me is very difficult. I do a lot of yoga and meditation. I'm really good at convincing myself I've compartmentalised all this stuff.

Ted Bundy at Leon County jail, Tallahassee, Florida, 1978. Photograph: © Bettmann/Corbis

What probably sets me apart from other lawyers – and it sounds silly and new-agey – is believing we're all connected. It saved me from having disdain for what I was doing. I'm always insecure, because I think I haven't done everything, that someone knows more than I know. So I overdo things – I drive my staff and my family crazy.

I still can't look at autopsy pictures without getting sick. There's only so much of the evil you can view without becoming burned out. You absorb it, and that's not good.

My father once said: "To keep our society free and democratic, someone has to do your job, and do it well." Then he paused and said: "I'm just really sorry it's you." I feel the same way.

• John Henry Browne's memoir, Sympathy For The Devil, is due out this year.

Irving Kanarek, 94, practised law in California from 1957-1989. He represented Charles Manson, who was convicted in 1971 of conspiracy to murder actor Sharon Tate and six other people. He also defended Jimmy Lee Smith, convicted of abducting and murdering an LA police officer in 1963, a case immortalised in the book The Onion Field.

Irving Kanarek: ‘I don’t dream or even think much about Charlie.' Photograph: Felix Clay for the Guardian

I would defend a client who I knew was guilty of horrific crimes. They have to be proved guilty. I've had cases where people were guilty as hell but they couldn't prove it. And if they can't prove it, he's not guilty. In that case, the person walks free. That's American justice.

I got a reversal of Jimmy Lee's death sentence, and he had been accused of killing a police officer. That made me the victim of police non-objectivity. They pulled me over, gave me tickets undeservedly.

It wasn't a difficult decision to take the Manson case. My purpose was to fight legally admissible evidence, and the amount of that was scant. His guilt was based on a few hearsay words, inadmissible in court, that he supposedly told this guy to do a number on the Tate residence. No question he was legally innocent. And, more than that, he was actually innocent. There was no evidence connecting him to those murders.

The newspapers, the magazines, the motion pictures got people all excited – Manson as the embodiment of human evil. Charlie wasn't a monster. When you look at the legally admissible evidence, you come to a very different conclusion. Just looking at him from objective considerations, he's a personable person.

Kanarek in court with Manson, 1970. Today, Kanarek says: ‘No question he was legally innocent. And, more than that, he was actually innocent.’ Photograph: AP Photo/Los Angeles Times

I've thought a lot about the case in terms of the legalities. I haven't dwelt much on the human tragedy of it. There's a lot of myth, for example that the baby was taken out of Tate's body. Not so. The wounds were not in the abdomen. The wounds were primarily in the breast area.

I didn't spend much time [thinking about Tate and the other victims], because they were victims of disputes that Charlie had nothing to do with. I think his direct involvement has been woefully extrapolated.

By the time I visited the house, the bodies were gone. The scene was what I'd call mechanical. Nothing about it was gruesome, per se. They'd marked where they were in chalk. So it isn't as overwhelming as some people may feel. None of it stayed with me. The tools of the courtroom make such scenes less than human. I didn't think about it emotionally. The victims are part of the case, but are not that tangible. I lost sleep on other cases, but not on this one.

People ask me, have I ever felt in the presence of evil, I don't know how to respond to that. I don't dream or even think much about Charlie.

I have regrets about every case where someone is killed or injured. Murder is unappetising. But I've never defended anyone who's been accused of horrible criminal acts on children.

Laurence Lee, 61, runs his own firm in Liverpool and specialises in criminal law. In 1993, he represented 10-year-old Jon Venables, who was charged with abducting two-year-old James Bulger from a shopping centre in Bootle, and murdering him. Venables and his co-defendant, Robert Thompson, were found guilty, becoming Britain's youngest convicted murderers.

Laurence Lee: ‘You couldn’t prepare for this.’ Photograph: Felix Clay for the Guardian

I describe it as the phone call of fate. The phone was ringing outside the solicitors' room at Liverpool magistrates court. It was always ringing, and no one ever answered it. On this day, I picked it up and the voice said: "You haven't seen Laurence Lee, have you?" I nearly dropped the phone in shock. The chance of it being me they were looking for was remote.

I'd been involved in a lot of drugs cases. Not many murders, just high-profile, stressful cases. You couldn't prepare for this.

I went to Lower Lane and met the boy. He looked more like an eight-year-old than a 10-year-old, and he was so convincing in the first interview that I believed he'd not been anywhere near the Strand shopping centre. He said he'd been on County Road near Everton's football ground with Robert Thompson.

After the break, the second interview started and the officers said: "We've spoken to Robert and he said you were in the Strand."

"We weren't in the Strand, we were on County Road, I told you," he said. Silence. "Well, we were in the Strand, but we never grabbed a kid, Mum."

That was the moment I knew. He wailed and screamed and got out of his chair and he hugged his mum and the police officer. I knew we were in for a rough ride then. It upsets me even now.

Jon Venables. Lee says that when he first met him 'the boy looked more like an eight-year-old than a 10-year-old.' Photograph: Courtesy of BWP Media via/Getty Images

That evening, I watched Crimewatch and saw this young lad who looked like Jon Venables wearing a mustard-coloured coat. I couldn't sleep. Before I left for work that morning, I looked out the window and thought that sitting on the wall across the road was an effigy of a baby. I put my glasses on, and it was something innocent. I couldn't wait to get back to the police station. I burst into the room and asked Venables: "What's the colour of your coat?" And he said: "Mustard."

Gradually, he revealed more about the Strand. He said they had just been messing about, and never hinted that any offence had been committed. I disappeared at lunch to give him a break, and when I got back at 2pm I was told that he had admitted killing James. "We did kill James. Please tell his mum I'm sorry."

He just came out with it to his mum. She had said: "Jon, I will always love you, but you've got to tell the truth." That's how responsible she was. He always maintained Robert Thompson was more to blame than he was. We argued that Thompson was the prime mover, and that it should be manslaughter rather than murder. But the prosecution wouldn't accept a manslaughter plea, so we pleaded not guilty.

The mood in the city was extremely angry, bordering on vengeful. After the boys' first appearance in court, I went to the window and I could see a baying mob hurling bricks at the police van that supposedly contained the boys.

I did think to myself, how the hell can children be so cruel? I never asked him how he could do it. I'd never do that to a client.

Albert Kirby, the detective in charge of the case, thinks they intended to kill him from the outset; that they were inherently evil. I disagree. They took James on a very long walk, and had many opportunities to kill him. They spent ages in a tropical fish shop, tapping on the tanks, asking if the fish were real. My theory is they intended to get him lost then didn't know what to do with him.

I was worried sick about the case and the repercussions for taking it on. In fact, the only call we got was from a woman who had a defective greenhouse claim. She said: "Mr Lee's handling my greenhouse. I'm not having him dealing with my greenhouse if he's dealing with this case." A few days later at a petrol station, a juggernaut driver, about 7ft tall, said: "Eh, mate, are you involved in that Bulger case?" I said yes. He said: "Well, I saw you on telly last night and I thought you were fucking great. Keep up the good work." I was buzzing after that. I thought, if I can get that faith from the Liverpool public, I've got no problems.

Taking on the case was a mix of principle and pragmatism. A criminal lawyer who refuses a murder case, no matter how gruesome, shouldn't be practising law. Simple as that. And if you've got ambition, of course you'll take it on. I had nightmares – a recurring dream about falling out of a ghost train at a fairground, and being run over. The case ended in November and I didn't get rid of my nightmares until I went on holiday in January. I also had terrible flashbacks. The day before the first appearance in court, I had to watch a video of the recovery of the body. I lifted up my glasses, so I couldn't see. That same day, I had to go to the police station to read the postmortem. What got me most was that a leaf was stuck to his foot. That made me cry. Awful.

Mr Justice Morland imposed a tariff of eight years, and there was uproar from the Bulger family. The Conservative home secretary, Michael Howard, increased it to 15 years. When the boys decided to challenge the ruling at the European Court of Human Rights, I stopped representing Venables. Until then, I used to visit him at his remand home. It was by then a year on from the trial, and the QC Brian Walsh said every time Venables saw me, he looked backwards, and that it was time to start rebuilding his life. We felt the best way of doing that was with new legal advisers.

James's mother, Denise, initially said they should never have been released. She then softened and said they should be released some day, but that eight years was too short. I have mixed feelings. If I was neutral, I think I'd say it wasn't long enough. But it was always a minimum of eight years, or as long as it took to convince the parole board they were fit to resume their place in society.

Venables obviously took the parole board in, because he reoffended [in 2010, he was jailed for downloading and distributing indecent images of children]. I was flabbergasted. Perhaps I shouldn't have been surprised. I have always thought they may be at liberty but they'll never be free. They've been looking over their shoulders ever since the judge released their identity, which I was furious about. Until then, they had been Boy A and Boy B. Having new identities, they had to reinvent their youth. That's enough to drive you to drink and drugs, and Venables did hit the bottle.

If I saw him now, I think I'd ask why he reoffended. I don't want to know about 1993, I'd say. You were given a chance to rebuild your life – what went wrong?

It's not a stigma being known as the Bulger lawyer, but it has had a profound impact on me. For a long time after the case, I never went to work. I had what I call post-Bulger syndrome. It's been vital for me to talk about it; it's a release. I'm not saying I would have ended up in a mental institution, but it's good to get it out.

William Kelley, 65, retired two years ago after practising law in Orange County, California, for 33 years. He defended Charles Ng, who was convicted of murdering 11 people. Ng and his accomplice, Leonard Lake, abducted and tortured their victims at a remote cabin in the Sierra Nevada foothills in the mid-80s.

William Kelley: ‘The Charles Ng case was top of the mountain for me.' Photograph: Felix Clay for the Guardian

I was really good at only one thing, and that's trying cases. If you like being in a courtroom, and I did, it's a real jolt, a rush. Especially if you have an interesting case.

I don't get emotionally involved with my clients. I made that mistake once and it wiped me out. I guess I'm pretty mercenary. Just bring 'em on and I'll defend them. It makes you a better lawyer.

The Charles Ng case was top of the mountain for me. I was flattered they even asked. My one hesitation was not that he was a monster, it was the amount of work. And I was right. Six years.

Was I horrified by my client? In the murder arena, you just don't have that sort of mindset. You're thinking, I'm going to do the darndest I can to defend this person as well as I possibly can. You want to prevail. You're battling the other side. Whether or not he gets off is up to the jury.

It was necessary to try to understand Charles Ng to defend him. Our relationship was not real cordial, because he was constantly criticising. I told him, I'm the experienced lawyer, we're going to do it my way.

The video tapes were tough. In one, Kathleen Allen is in chains. They're talking to her, telling her she'll do their bidding, that they're going to keep her captured. She's terrified. It's hard to see that stuff. The first time I saw that I was like, wow. But I was also thinking, man, that's a bad piece of evidence. Brenda O'Connor is on another tape. She wants to know where her baby is. She's resisting, arguing and aggravated. They say: "We've given your baby away, he's fine." That wasn't true. The baby was never found. They lay a gun on the table. They're basically saying, you're ours now. Stunned silence when you see that. I don't remember if I could sleep that night, but my guess is probably not. I watched it dozens of times after that. The impact does lessen, because you're looking for anything in there.

Charles Ng. Kelley says his one hesitation about taking the case 'was not that he was a monster, it was the amount of work. And I was right. Six years.’ Photograph: AP Photo

The courtroom was packed, standing room only, every day. Some of the victims' relatives hated me. You can't try murder cases successfully if you get emotionally involved with the victims. You have to be very, very objective. And kind of cold. You can sympathise at some level, think about it on the first day when they're in the gallery crying. But once that gavel comes down and the game starts, that's it, they're just not part of what you're doing.

You have to be able to project when you need an emotional reaction from the jury, know how to push that button. The courtroom is a theatre of persuasion. You do what you need to do – within the bounds of ethics.

When the case was over, I was exhausted. I took off by myself and went to Ireland. Guinness therapy. Guinness and golf.

I'm really glad I did the Charles Ng case, but I'd never do it again. It just takes too much out of you. I had a relationship that ended, and this case had a lot to do with it. It never leaves you.

I have some of Charles's origami pieces on the mantelpiece. I supposed it's odd. He was artistic, a very creative guy. I like art. Having them here reminds me of the whole experience.

• This article was edited on 27 June 2014. In the original, we said that during his 33 years' practising law, William Kelley had worked for 22 of them as a prosecutor, when he was in fact a defence lawyer. This has been corrected.