Actress Kristin Harmon, sister of Mark Harmon, dead at 72

Actress and painter Kristin Harmon, the older sister of "NCIS" actor Mark Harmon and the ex-wife of former pop star Ricky Nelson, died April 27 of a heart attack. She was 72.

Harmon's "sudden and unexpected" death was confirmed by her daughter Tracy in a touching Facebook post May 1. Tracy added that Harmon had also been put into a coma for an undetermined amount of time last year to treat a lung infection.

"No one could blow the house down like she could. And no one could make something out of nothing like she could," Tracy wrote. "She knew where the party was, she WAS the party. She didn't just know the cool people, she WAS the cool people."

See early photos of Kristin Harmon, Mark Harmon and Kelly Harmon:

Harmon was born in 1945 to 1940 Heisman trophy winner Tom Harmon and actress Elyse Knox. She was the older sister of actor Mark and model and "Bay City Blues" actress Kelly.

The blonde met her future husband Ricky Nelson at just 12 years old, and they were wed six years later in 1963.

That same year, she joined her husband's family's radio and TV series "The Adventures of Ozzie and Harriet," on which she appeared in 29 episodes as Ricky's on-screen wife.

The couple, who also appeared together on screen in "Love and Kisses," had four children: actress Tracy, twin sons Gunnar and Matthew, who went on to form the band Nelson, and son Sam.

But there was trouble in paradise for the two, whose marriage quickly descended into a drug-fueled spiral.

"At first we were in it together. I tried to be one of the guys, to fix the marriage by going on the road and being involved in road stuff that is really not good for anyone. After a while we were totally messed up, both of us," she told People in 1987. "I got into therapy and so did he for a while but then he started not showing up… I knew that if I didn't leave, we would both die. I knew that I would just somehow try to make it for my kids. I couldn't help Rick anymore."

See photos of Mark Harmon through the years:

Harmon filed for divorce in 1977, but the couple reconciled — only to split again in 1980. Their divorce was finalized two years later after years of he-said, she-said over drug and alcohol use.

After Nelson was killed in a plane crash in 1985, Harmon entered rehab at the behest of her brother, Mark.

She and her sibling's relationship was further strained when Mark and wife Pam Dawber were awarded temporary custody of a then-12-year-old Sam in 1987 amid accusations that Harmon's drug use had made her incapable of taking care of her son.

Harmon later regained custody following a contentious war of words, though Mark won visitation rights.

She was married again to Mark Tinker in 1988, and they split in 2000.