On the first day of the Travis Vader murder trial in March, the accused killer's lawyer criticized what he called the RCMP's "negligence and inept investigation."

Brian Beresh said the Mountie who "mishandled" the McCanns' motorhome fire — a key crime scene site for possible evidence in the disappearance of the St. Albert, Alta., couple Vader is accused of killing — was "eventually fired by the RCMP."

That's what Beresh thought, but he was wrong.

Const. Liam MacNeil is still a Mountie. And he's in trouble again.

The mistakes MacNeil made in July 2010 have been damaging and costly on a number of levels. His career has never been the same.

The Marie and Lyle McCann missing persons investigation was damaged from the start. That led to millions of dollars spent by the RCMP to try and play catch up.

We also now know the RCMP did not tell the media or the public the whole story in the early days of the investigation.

Motorhome fully engulfed in flames

MacNeil became an RCMP officer in 2009 and was posted to Edson, Alta. Only a year into the job, he was sent to a campground near Minnow Lake shortly after 7 p.m. on July 5, 2010, to assist the Edson Fire Department with a vehicle fire.

When he got there, a motorhome was fully engulfed in flames.

MacNeil was called to investigate the McCann's burned-out motorhome at a campground near Minnow Lake on July 5, 2010. (RCMP)

According to a 2013 RCMP disciplinary decision obtained by CBC, MacNeil's "initial investigative steps were adequate."

The report states he "quickly recognized the suspicious nature of this fire given the awkward position of the parked vehicle and the significant monetary value of the motorhome."

Instead of securing the scene, once the fire was out MacNeil contacted a towing company to have the burned-out motorhome taken away and left before the tow truck even arrived. - CBC News investigation

That night, MacNeil took photos and seized limited evidence. But he didn't interview the owner of the campground or any of the other campers. He spotted fresh tracks next to the driver's side of the motorhome leading into the nearby bush, but did nothing to investigate them.

At the time, the rookie constable thought he was likely dealing with a stolen vehicle or an insurance fraud case, according to the disciplinary decision. But instead of securing the scene, once the fire was out MacNeil contacted a towing company to have the burned motorhome taken away. He left the scene before the tow truck even arrived.

Forgotten messages

MacNeil used the motorhome licence plate to determine it belonged to the McCanns. Back at the Edson detachment, MacNeil made one phone call to try and reach the McCanns but got no answer.

He called the St. Albert RCMP detachment and spoke to a clerk, who told him how to contact their investigators through the Canadian Police Information Centre (CPIC). MacNeil claimed in his report that he sent a CPIC message asking St. Albert RCMP officers for help locating the McCanns.

I think from the get-go that it has been a botched investigation ... I'm embarrassed. - Bill Pitt, retired Mountie and criminologist

It was a false claim. MacNeil later revealed he forgot to send the CPIC message. So Mounties never knocked on the McCanns door or checked with their neighbours. It was five days before the McCanns, who had been headed on vacation, were reported missing. By then, the trail had gone cold.

At the time, the RCMP was sharply criticized for the handling of the case. Retired Mountie and criminologist Bill Pitt likened the force to keystone cops.

"Well I think from the get-go that it has been a botched investigation," Pitt said in 2010. "I think five precious days have been lost. I think the lives of two people lie in the balance. I'm embarrassed."

RCMP spin doctors scrambled to put on a brave face, but they didn't share the full truth.

'They dropped the ball'

Patrick Webb, a former RCMP sergeant who is now retired, assured the media in 2010 that, after finding the burned RV, police called the couple's home repeatedly and officers knocked on the door of their St. Albert home, but couldn't locate them.

"At the time, it was more of a case to try and just get a hold of them," Webb said. "There was no report at that time that they were missing. It was simply just an effort to try to contact them."

But now it is known, according to the RCMP disciplinary decision, that "effort" consisted of a single phone call.

When the McCanns were reported missing on July 10, 2010, a news release sent out the next day by St. Albert RCMP indicates they either didn't know about the burned RV, or else they were unwilling to publicly connect the dots. The release says "the motorhome was last seen in the Edson area around July 5th."

Pitt told the Globe and Mail at the time: "It's either a lazy investigation, dumb investigation, or a combination of both, but they dropped the ball."

At the end of that week, RCMP Deputy Commissioner Peter Hourihan faced the media and acknowledged mistakes had been made.

"I respect that public confidence is contingent upon police competence," he said. "And I want to assure you we are doing everything we can with the best people we can to make sure that we follow up on everything that we can."

Hourihan revealed the Mountie who made mistakes with the motorhome crime scene had been placed on administrative leave. He did not name Const. Liam MacNeil.

Const. MacNeil was a year into the job when he became involved in the McCann investigation. (RCMP)

MacNeil docked 5 days pay

MacNeil returned to frontline duty in Edson later in 2010, but got into trouble on the job again in October over improperly handling exhibits and failing to fully investigate a hit-and-run.

In July 2011, MacNeil was charged with two counts of disgraceful conduct and served with a notice of a disciplinary hearing.

Eight months later, there was a recommendation for MacNeil's discharge. Instead, the constable went on a medical leave that appears to have lasted for a year. MacNeil has been diagnosed with a medical condition, but the details of the diagnosis are covered by a publication ban.

MacNeil's disciplinary hearing was fast-tracked so it could be conducted by video conference on July 23, 2013. The two counts of disgraceful conduct were changed to neglect of duty by consent.

MacNeil pleaded guilty, and was docked five days pay. A letter of severe reprimand was also put in his file, and he had to sign an undated voluntary resignation form in order to remain a Mountie.

At the hearing, MacNeil offered what the disciplinary decision called "a sincere apology" to the McCanns "for compromising the investigation into their disappearance."

By that time, the constable was back on the job, temporarily transferred to the Hinton detachment.

'I saw my whole life evaporate before my eyes'

MacNeil testified at his second disciplinary hearing last month in Hinton.

"When I started in Hinton, I was advised I would be monitored closely for my performance and even an allegation of a code of conduct for even a minor infraction could be fatal for my career," he said.

MacNeil, in the forefront, at a disciplinary hearing. (Janice Johnston/CBC)

MacNeil's supervisor testified his performance had "peaks and valleys," but there were no serious problems until June 2014.

That's when the constable agreed to help a Hinton mother track down her troubled adult son and used police databases to obtain information. He's accused of sharing some of that restricted, privileged information with the woman, a violation of RCMP protocol. At the time, MacNeil didn't think he'd done anything wrong.

The whole premise of what we do is based on honesty, integrity, professionalism. - Sgt. Danny Knight, MacNeil's supervisor

MacNeil's supervisor confronted him about the breach. Sgt. Danny Knight also testified at the disciplinary hearing last month.

"I was absolutely confident that I had been lied to about this," he said. "It's a fairly egregious thing. The whole premise of what we do is based on honesty, integrity, professionalism. I can't overlook it and say it's a one-off, a mistake and leave it at that."

MacNeil testified his boss had mentioned the possibility of a code of conduct investigation, and he panicked.

"I saw my whole life evaporate before my eyes," MacNeil told the disciplinary hearing.

"A pain went across my chest. I thought that was the end of my RCMP career. I saw everything I worked for in my life slip away. I didn't know how I was going to tell my wife my career was over. That we were going to have to rely on her income. And that I'd just kissed the last seven years of my life goodbye."

Formal charges laid

MacNeil kept going in to work at the Hinton detachment. But in August 2014 he was ordered to turn in his uniform and keys. The constable was given two options — resign or take a medical pension. He refused to do either. MacNeil still wanted to be a Mountie.

I saw my whole life evaporate before my eyes. A pain went across my chest. I thought that was the end of my RCMP career. - Const. Liam MacNeil, at his disciplinary hearing

The next month he wrote a letter to the RCMP K-Division commanding officer to formally revoke his signature on the voluntary resignation form he signed the year before.

An internal email sent in September 2014 from a high-ranking Mountie to other superior officers was read aloud at the disciplinary hearing.

The staff sergeant wrote: "It looks like Liam won by not picking an option. Who would have thought? Looks like the (voluntary resignation) is not worth the paper it's written on."

MacNeil was formally charged with three counts of discreditable conduct in July 2015.

His three-day hearing, covered only by the CBC, was held in Hinton at the end of March.

During the hearing his lawyer, Nicole Jedlinski, accused the RCMP of unfairly targeting MacNeil.

"It seems like they want Const. MacNeil to leave the RCMP no matter what," she said. "The evidence points to a consistent pursuit by the RCMP to end Constable MacNeil's career."

Jedlinski added: "It may not have been looked at the same if it was a different officer."

After two days of testimony, the lawyer asked to have the charges against MacNeil quashed, citing an abuse of process.

The case now hangs in limbo. The RCMP disciplinary website does not indicate if MacNeil still faces disciplinary charges, or if his lawyer successfully got them thrown out.

MacNeil is still a Mountie. He declined to comment when contacted by CBC News.

MacNeil is expected to testify sometime this month at the Vader murder trial.

janice.johnston@cbc.ca

@cbcjanjohnston