Phil Hartman is known by generations of Americans for his comedic genius, from his roles on “Saturday Night Live,” "NewsRadio" and “The Simpsons.”

Hartman, it seemed, had achieved the American dream; in about two decades, he had perfected his craft and built a family. But in 1998, he was violently killed at the hands of his wife.

“I think in my old age, I've come to realize just how precious everything is and I try to value the many blessings that have been bestowed upon me,” Hartman reflected in a 1998 interview. “But there's also this sense of vulnerability if fortune took a turn for the worse, and that you live with the awareness that anything could happen in this world.”

Hartman dabbled in a couple of other careers before finding comedy. He started out as a roadie for a band called Rockin’ Foo, according to Mike Thomas, author of the biography “You Might Remember Me: The Life and Times of Phil Hartman.”

Thomas said Hartman was living a “bohemian existence” where pot was plentiful. Around this time, he met Gretchen Lewis, who would go on to become his first wife.

Steve Small, Hartman’s close friend and lawyer, told “20/20” that “Phil fell in love easily, but … wasn't very skilled at continuing a relationship.”

Hartman married Lewis in 1970. By 1972, the two had divorced.

By the mid-70s, he was working for his brother’s talent management agency. Using the graphic arts skills he honed in college, Hartman designed classic rock album covers, including the cover for America’s “History: America’s Greatest Hits” album and the simple line drawing of a horse on Poco’s “Legend” album.

But it was his desire to branch out of his, as he called it, “very introverted lifestyle” that would launch his comedy career. In 1975, he attended a show by the Los Angeles improv group The Groundlings, which invites audience members up to the stage. Hartman volunteered.

“I never saw an audience member come up with that kind of excitement and energy…it was like a hurricane hit that stage, and I mean in a good way,” said Tracy Newman, comedian and founding member of The Groundlings.

Ron Galella Collection via Getty Images, FILE Phil Hartman attends the 23rd annual People's Choice Awards, Jan. 12, 1997, at the Barker Hangar in Santa Monica, Calif.

The group thought he was so good that they invited him to join the troupe, while he also took classes there.

In 1982, Hartman married his second wife, Lisa Jarvis.

“My sense of Phil was that he was really two people,” Jarvis told “20/20.” “He was the guy who wanted to draw and write and think and create and come up with ideas. He was the actor [and] entertainer, and then he was the recluse.”

“Seeing Phil at The Groundlings was Phil being truly Phil,” she continued. “You know, as time goes by, you understand that his personas are his protection and [they] are his personality.”

But after only a year of marriage, she said she realized the relationship was over.

“On our first anniversary, we went back to Santa Barbara. And I dressed up... lingerie or something … and I jumped up on the bed… and he said, ‘Must you? Really?’ So I said, ‘No.’ I took it off, put a robe on, got my book out. And I knew that was the end.”

It wasn’t long after their divorce that Hartman met Brynn Omdahl.

Born Vicki Jo Omdahl, she grew up in northern Minnesota in a family of four children. Her brother, Greg Omdahl, said they had an “idyllic childhood.”

“She was always the instigator of fun,” Greg Omdahl said.

Brynn Omdahl moved to Los Angeles in her 20s with dreams of becoming a model and actress. She signed with a modeling agency, which helped her find work as a swimsuit model for Catalina swimwear. Meanwhile, she also went on auditions.

The LIFE Picture Collection via Getty Images, FILE Actor Phil Hartman and wife Bryn.

“I remember she was gonna try out for ‘Hee Haw,’ to be one of the ‘Hee Haw’ girls that pops out of the corn stalks,” Greg Omdahl said.

During her time in L.A. in the 1980s, though, her brother said she developed an addiction to cocaine. “She had a problem with cocaine,” he said. “She did too much cocaine.”

Greg Omdahl said he told her she needed to go to rehab. “I talked her into going through treatment,” he said.

“As with Lisa, as with Gretchen, it becomes very intense very fast,” Mike Thomas said about Hartman’s relationship with Brynn Omdahl. “But as the months go on, the cracks begin to show and Phil does what he did with his last two relationships — he begins to withdraw emotionally. They begin this pattern of fighting and making up and fighting and making up that would mark their relationship from there on out.”

Hartman’s career takes off

Hartman spent 11 years at The Groundlings while getting more work. That included the role of “Captain Carl” on the “The Pee Wee Herman Show”, where he co-starred with fellow Groundling Paul Reubens.

His big break would come in the fall of 1986 when Hartman joined the cast of “Saturday Night Live” as a writer and performer.

Hartman joined a cast that included Jon Lovitz, Dana Carvey and Kevin Nealon. During his time on the show, Hartman played a wide range of characters, including Johnny Cash, Frank Sinatra, televangelist Jim Bakker, Ed McMahon, former President Ronald Reagan and even Jesus. But his most memorable role was his impression of Bill Clinton.

R.M. Lewis Jr./NBC via Getty Images, FILE Sean Penn, left, and Phil Hartman during the "Discover" skit on "Saturday Night Live," Oct. 24, 1987.

“Phil was on the map with ‘SNL’ like never before,” said Thomas of his take on Clinton.

In 1987, one year after Hartman joined “SNL,” Phil married Brynn Omdahl. It was his third marriage.

The couple welcomed their first child, a boy whom they named Sean, in 1988. After Sean was born, his ex-wife Lisa Jarvis says Phil Hartman called her.

“He calls me and [says], ‘I just became a father.’ And so, I wrote a card. ‘Dear Phil and Brynn, you know... much love from Aunt Lisa. You know, if you ever need a babysitter... I'm so thrilled for you,’” Jarvis said.

Jarvis said she “got back a letter that was hair-curling, fury, rage and [a] death threat from Brynn… The gist of it was, ‘Don't ever f---ing get near me or my family or I will hurt you. I never want to hear from you…never, ever, ever come near us or you will really be sorry.’”

Courtesy of Greg Omdahl Phil Hartman was father to son Sean and daughter Birgen.

Meanwhile, Phil Hartman was soaring professionally. In 1989, he won an Emmy as part of the writing staff on “SNL.”

In 1991, while still an “SNL” cast member, Phil Hartman started working on “The Simpsons,” where he voiced two iconic characters: fading B-movie actor Troy McClure and sleazy lawyer Lionel Hutz.

“Phil made the material funnier than we originally imagined, and I couldn't imagine anybody else doing it,” said Al Jean, the show’s executive producer.

The Hartman family welcomed their second child — a daughter whom they named Birgen — in 1992.

“I remember him calling me when Birgen was born,” said Lynne Stewart, a friend of Hartman’s who played Miss Yvonne during his time with “Pee Wee’s Playhouse.” “He was very, very choked up... He said, ‘She's the most beautiful baby in the world.’”

Greg Omdahl also spoke to the Hartmans’ love for their children, saying, “When I watched the old home videos of Brynn and Phil and their kids, it really brought home what loving parents they were...and what a great mother she was.”

Joel Diamond, a friend of the couple, said that “Brynn was the greatest mom; she was wonderful.”

Courtesy of Greg Omdahl Greg Omdahl also spoke to the Hartmans’ love for their children, saying, “When I watched the old home videos of Brynn and Phil and their kids, it really brought home what loving parents they were...and what a great mother she was.”

But as the Hartman family grew, so did Phil Hartman’s work schedule. In addition to “SNL” and “The Simpsons,” he also did commercials for brands like Cheetos and McDonald’s and became a regular on the late night talk show circuit.

“He wasn’t home nearly as much as she wanted him to be to take care of the kids — to be with her,” Thomas said.

Biographer Mike Thomas said he thought Phil Hartman “might have liked the idea of fatherhood a bit more than actually putting in the hard work that fatherhood requires. Because he was always working. And Brynn was resenting him more and more because of that.”

Greg Omdahl added that, at times, Brynn was jealous of her husband’s celebrity status.

“Phil was getting a lot of attention and [Brynn] wasn't getting any attention… I suppose some of that's natural,” Greg Omdahl said. “She just wanted to be more part of the spotlight than she was, you know.”

With money pouring in, Phil Hartman bought boats, cars and a small airplane. He would spend time away from the family in Catalina Island, his favorite place in the whole world.

“Maybe she felt Phil was spending too much time with his boat or airplane… [and] not enough time with the kids,” Greg Omdahl said. “I would kind of reassure her that that's normal and that he still loved her.”

Phil Hartman’s makeup artist on “SNL,” Norman Bryn, remembered one fight he overheard the couple having behind doors of an “SNL” dressing room, saying that Phil Hartman walked away from it “white as a sheet.”

“I said, ‘Phil, what's the matter?’ And he said in a comedy Phil Hartman voice, ‘Well, Norm, looks like the wife's gonna divorce me this time,’” Bryn said.

Phil Hartman decided to leave “SNL” in 1994 after eight seasons on the show. He worked to develop his own variety show, “The Phil Show,” but the project wasn’t picked up, so in 1995, he signed on to an NBC sitcom called “NewsRadio.”

The comedian also landed big parts in movies. In 1996, Hartman starred with Steve Martin in “Sgt. Bilko.” He was also in “Jingle All the Way” with Arnold Schwarzenegger.

Meanwhile, Brynn Hartman got two very minor roles — she had one line in the Rob Reiner movie “North,” where she played a cocktail waitress.

She also appeared in an episode of “Third Rock from the Sun” as an alien from Venus. According to friends, she was hoping for more work.

And her substance abuse had not gone away. Phil Hartman’s “NewsRadio” co-star Andy Dick told “20/20” that during a Christmas party in 1997, he gave Brynn some cocaine after she asked if he had any.

Dick asserts that he did not cause her to relapse: “She was already in relapse mode, which I didn't even know she had a problem [with] at all in the first place.”

“Brynn had low self-esteem. She worried about looking older, getting older,” Phil Hartman’s friend Dawna Kaufmann added. “The month before they died, Brynn turned 40… For many women, a 40th birthday is a big line in the sand. An emotional event.”

She was also taking the anti-depressant Zoloft.

Greg Omdahl recalls, “She talked about having anxiety at times.”

Though some say they were fighting more than usual by this time, Greg Omdahl remembers it differently.

“They had seen a counselor and both of them said that really helped and [that] they’re trying to improve for their spouse. I mean, they cared that much about each other,” he said.

Tragedy strikes the Hartman family

The exact details of what happened the night of May 27, 1998, and into the morning hours of May 28, 1998, remains somewhat of a mystery to this day.

“I was waiting for [Phil] to come home, because it was going to be the time for me to go,” the family’s babysitter Lorraine Moss said of that day. “Brynn had just gone out and she wasn't going to be back till late. So Phil was going to take over in taking care of the children.”

Courtesy of Greg Omdahl Phil and Brynn Hartman welcomed their first child, a boy whom they named Sean, in 1988.

Brynn Hartman went out for drinks that night with her friend Christine Zander before driving over to her friend and former lover Ron Douglas’ house at around 10:15 p.m.

Douglas declined ABC News’ requests for comment, but according to what he told police, Brynn Hartman had a few beers and complained to him about her husband. He told police she left his house at around 12:45 a.m., got into her car and returned home.

Sean Hartman would reportedly later tell police that he heard sounds he likened to “the slamming of a door.”

At 3:45 am, as Ron Douglas would recount to police, he was awoken by someone’s pounding on his front door. It was Brynn. She told Ron, “I killed Phil. I don’t know why.”

Douglas told police he didn’t believe her at first. But then, a gun fell out of Brynn’s purse. He took it away from her and put it in the trunk of his car.

The two drove in separate cars back to the Hartman home, where Douglas found Phil’s body in his bed. Police would later discover he had been shot three times. Ron stepped into the hallway to call 911. And then, he discovered Brynn had locked herself in the master bedroom.

It was about 6 am and the quiet street in Encino, California was suddenly swarming with police, news cameras, and a gathering crowd of onlookers. Ron handed the gun to police, but they had no idea if there were any other weapons in the house.

As nine-year-old Sean and six-year-old Birgen were being whisked to safety, another shot rang out. When police reached the master bedroom, they were greeted with silence.

“We go through the door, we find a man [lying] on the bed, he has a bullet hole through his forehead. There's a woman [lying] next to him, and she also has a gunshot wound,” responding LAPD officer Daniel Carnahan said. “Looking at the bodies it's obvious… that they were not alive.”

Brynn had killed herself after taking Phil’s life.

“For me it is one of the most tragic scenes… [Hartman] had actually experienced the American dream that most people don't get to experience,” Carnahan said. “To have that taken away in this fashion seems so contradictory and so out of place and so unfair.”

The children were taken into police custody. Upon hearing the news, Diamond went to the police station and asked if he could take the kids out of the police station. He said police told him he could take them to a nearby park.

“I remember I was pushing Sean on a swing… I said, ‘Sean…is there anything I could do for you?’ And he said, ‘No.’ He said, ‘My mom promised me she'd take me to a lot of fun places and now she'll never be able to,’” Diamond said. “Birgen looked like she was more in shock than anything else. And I remember her saying, ‘I know I'll never see my mommy and daddy again.’ I don't know how she knew, but it was one of the worst days of my life, seeing those kids.”

Los Angeles County medical examiner Craig Harvey later determined that Brynn Hartman had a blood-alcohol level of 0.12, as well as cocaine and Zoloft in her system that night.

At one point, Andy Dick says Phil Hartman’s “SNL” co-star Jon Lovitz blamed him for causing Brynn Hartman’s relapse, and in turn, the unthinkable murder-suicide.

“Jon loved Phil and I know he was angry and he probably wanted somebody to blame in a sense,” said Vicki Lewis, who played Beth on “NewsRadio.”

“I didn't cause her to relapse. That's one of the misconceptions. That is not true. Not true. Like, for real,” Dick said. “I didn't cause her to relapse and I didn't give her cocaine and then she ran off, got a gun and shot her husband and herself. No…that happened six months later.”

ABC News reached out to Jon Lovitz who declined to comment.

“I've lost a sister that was such a wonderful person and a brother-in-law who was wonderful,” Greg Omdahl said.

He said the murder-suicide “was like getting punched in the gut because I knew my sister would never murder anyone. It was such a hard thing to face.”

A year after the murder suicide, Greg Omdahl filed a wrongful death lawsuit against Pfizer, the maker of Zoloft, on behalf of the Hartman estate.

Omdahl said, “I did file a lawsuit against Pfizer… alleging that the use of Zoloft caused my sister to not to know what she was doing, and she shot her husband. And when she came out of that, she shot herself.”

When the lawsuit was filed in 1999, Pfizer gave a statement to Salon Health that “there’s no scientific or medical evidence that Zoloft causes violent or suicidal behavior.” The suit was settled for $100,000 and there was no admission of any wrongdoing.

Brynn’s sister Cathy and her husband raised both Sean and Birgen in the Midwest. Greg Omdahl said that “they grew up as loved children.”

Courtesy of Greg Omdahl The couple welcomed their first child, a boy whom they named Sean, in 1988.

Sean is now 31 years old and pursuing his dreams of being an artist and musician. Birgen, 27, married recently and started a business “that’s doing [really] well,” Greg Omdahl said.

He added: “I believe my sister would be very proud of how Sean and Birgen have grown up and the people they've turned into.”

ABC News' Allison Hope Weiner contributed to this report.