Mark Harmon's sister Kristin dead at 72

Mark Harmon's sister Kristin Harmon has passed away.

The artist and actress, who was known for her role in The Adventures of Ozzie and Harriet and for her marriage to Ricky Nelson, died after suffering a heart attack on April 27, 2018, according to the New York Daily News. Kristin was 72 years old.

In a post on Facebook, Kristin's daughter, Tracy Nelson, revealed that the Love and Kisses star had faced health problems in recent years, having been placed in a coma as doctors treated a lung infection in 2017. She apparently surprised doctors when she eventually recovered from the illness, as they thought it would have killed her.

As noted by People magazine, Kristin and her husband battled substance abuse issues during their marriage, following the births of their four children, daughter Tracy, twin boys Gunnar and Matthew, and son Sam. "After a while we were totally messed up, both of us," Kristin told People back in 1987. "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 later divorced her husband, but she continued to use drugs and alcohol. Following Nelson's untimely death in 1985, she reportedly spiraled before eventually accepting help from her brother, NCIS star Mark Harmon, who urged her to enter rehab. "Nobody but my brother could have talked me into this because I trusted him," Kristin shared. "A voice inside me said, 'For once in your life, let somebody help you.'"

However, their relationship later became strained when Mark and his wife sought full custody of Kristin's youngest child, who was 12 years old at the time. The couple had previously been granted temporary custody of Sam (via the Daily Mail). However, they eventually dropped the case, and Kristin retained custody while Mark was granted visiting rights.

At the time of this writing, Mark has yet to release a statement regarding his sister's passing.