Mark Harmon has been in the entertainment industry his entire adult life. Though he’s had a long and storied career, the last 20 years have been almost entirely focused on his role as Leroy Jethro Gibbs on the hit television show NCIS, for which he’s been nominated for Emmys and other awards.

In just a matter of years during his youth, Harmon transformed from football hunk to a great actor. At the same time, he’s been very quiet about his private life, always putting his family first.

Mark’s father, Tom Harmon, was an All-American football player who won the 1940 Heisman Trophy. He was even the No. 1 pick in the NFL Draft in 1941. But the older Harmon gave up his football career to become a fighter pilot in the second World War. After the war, he found a career in TV sports. Harmon’s mother, Elyse Knox, was an actress. Harmon also grew up with two sisters, Kristin and Kelly.

Both of his sisters pursued careers in the entertainment industry: Kelly became a model and actress, and Kristin worked both an actress and a painter.

Kristin, born on June 25, 1945, was the oldest among the Harmon siblings.

But sadly, she is no longer with us. Kristin tragically passed away in 2018.

She faced a challenging life marked by marital difficulties, substance abuse struggles, and even a period of estrangement from one of her children. Many people might not know this – but Mark Harmon actually played a significant role in supporting his sister during her difficult times. He even took temporary custody of her youngest son when Kristin was unable to provide proper care.

At the outset, Kristin’s life seemed to be shaping into a true Hollywood tale. She was just 12 when she first met the man who would become her future husband – the legendary actor and musician Ricky Nelson.

Around 1961, Kristin Harmon and Ricky Nelson began dating. Kristin was from a similar background, as she also was raised in Hollywood. Additionally, her family and the Nelsons were close friends.

The two married in April 1963 and stayed together for 19 years. Kristin was just 17 and Ricky was 23 when they tied the knot

They had four children: Sam Hilliard Nelson, twins Matthew Gray Nelson and Gunnar Eric Nelson, and their daughter, Actress Tracy Kristine Nelson.

Ricky Nelson was a huge teen idol at the time and his popularity continued to increase throughout the ’60s as he consistently came out with top 40’s hits. His popular music was in the growing rock n’ roll genre and led to various tours for him over the years.

Kristin’s career also saw a steady rise as she began appearing on The Adventures of Ozzie and Harriet, one of the most popular TV shows of all time. She also had some more prominent roles, but after a while, her marriage to Ricky Nelson began to crack – and Kristin’s problems in her personal life would eventually destroy her.

The hard-partying lifestyle and everything that came with being married to a rock star began to exact its toll. Eventually, Kristin found herself caught in a downward spiral from which she couldn’t escape.

”We were hippie rock n’ rollers. We did what everyone else was doing all those years,” Kristin told People in 1987 and added:

”I got into therapy and so did he for a while but then he started not showing up. I tried telling my family, there’s a drug problem here and we’ve all got to help. But they totally denied there was anything wrong.”

Kristin and Ricky separated and came close to divorcing in 1975 but decided to reunite and work on their marriage. However, prior to their reconciliation, Ricky was discovered cheating with two cheerleaders. He later claimed he had been set up so that Kristin could win custody of the kids.

Although the famous couple briefly reconciled, they eventually separated again, ultimately finalizing their divorce in 1982.

Tragically, Ricky Nelson died in 1985 in a plane crash. The singer’s death was a freak accident, where a heater in an airplane caused a fire, killing all passengers except the pilot. The horrible event exacerbated Kristin’s bad behavior, and while her older children had already moved out, her son Sam continued to reside with her.

The situation at Kristin’s house started to become untenable, as evidenced by several incidents. Once, Mark Harmon encountered his sister while she was grocery shopping, and it was evident that she was under the influence. Shortly thereafter, the NCIS actor successfully persuaded her to seek treatment.

”Nobody but my brother could have talked me into this because I trusted him. A voice inside me said, ‘For once in your life, let somebody help you’,” Kristin told People.

It soon became apparent that Sam no longer wanted to live with his mother.

Sam was 13 years old at the time and his maternal uncle actor Mark Harmon with his wife, actress Pam Dawber, filed a petition for his custody.

Harmon claimed that his sister Kristin was dependent on drugs and hence could not parent the 13-year-old boy. The trial received a lot of media attention and brought to light many private and not-so-pleasant details. During the trial, Sam’s psychiatrist testified that the 13-year-old boy described his mother as a dragon, expressing concerns about her mood swings and how she restricted his interactions with his siblings.

It’s was a tough time for the whole family and no one knew what to expect regarding the outcome of the custody battle.

But after some time, Mark Harmon withdrew his petition after his sister made some shocking allegations of cocaine use by his wife, Pam Dawber. According to OK! Magazine, Kristin’s attorneys said that Dawber had used cocaine while working on the set of Mork & Mindy, a show that aired from 1978 to 1982 and starred the late Robin Williams

Finally, the NCIS star and his sister reached an agreement and emerged from the court arm-in-arm. Nelson maintained custody, while Harmon was granted visitation rights. Kristin told reporters that she and her brother would now try to mend their relationship. Kristin, Mark, and Sam also reached an agreement to participate in family therapy.

Harmon chose not to comment on anything after the proceedings. However, his lawyer issued a brief statement and said that: ”I think they all realized that this was tearing the family apart”.

Fortunately, Kristin and Sam’s relationship started to heal after the bitter feud.

”As you get older, things that were important aren’t important anymore. Problems aren’t problems anymore. You work through them, or you don’t. But for the most part, you hope to. I think we’re in a good way together, and we have a good relationship,” Kristin said in 2016.

Last years and cause of death

One year after the custody battle, Kristin tied the knot with TV producer and director Mark Tinker. Their marriage lasted for 12 years until their divorce in 2000.

During her final years, Kristin largely lived a life away from the public eye. Tragically, on April 27, 2018, she experienced a fatal heart attack. She was 72.

According to her daughter Tracy, Kristin ”passed away suddenly and unexpectedly.”

”A force. A reckoning. Artist, first, always. Anarchist, bohemian, beauty. Hurricane Kris,” Tracy wrote in a Facebook post and added:

”No one could blow the house down like she could. And no one could make something out of nothing like she could.”

Mark Harmon has maintained silence regarding his relationship with Kristin over the years, making it challenging to determine the nature of their closeness at the time of her passing.