Robert Wagner wishes Hart to Hart wife a happy birthday weeks before anniversary of late wife Natalie Wood's drowning

Robert Wagner on Monday took to Instagram to wish Hart to Hart costar Stefanie Powers, who played his wife on the series, a happy 84th birthday.

'Happy Birthday, Mrs. H!' Wagner, 96, said in the social media post. 'Wishing my favorite partner in crime-solving a fabulous birthday! Some things never go out of style… especially you!'

Wagner, who has been married to Jill St. John since 1990, portrayed Jonathan Hart to Powers' Jennifer Hart over five seasons of the series spanning 1979-1984.

They portrayed the wealthy sleuthing couple who would solve crimes on the show, which was created by the late Sidney Sheldon.

Wagner and Powers revived the roles on the films Hart to Hart Returns (1993) and Hart to Hart: Till Death Do Us Hart (1996).

The Daily Mail has reached out to representatives for Wagner for further comment on the story. 

Powers last month told People Wagner had recommended her for the show after they collaborated on his past series It Takes a Thief.

'We not only were friends, but... it doesn't always follow suit, that just because you're friendly with someone that you're going to have chemistry on the screen,' Powers told the outlet. 'We were just really, really lucky to have that chemistry and continue it throughout the years.'

She said that she and Wagner 'talk to each other quite often,' and compared him to a brother.

Powers said, 'He's a tremendous part of my life, and I love him dearly.'

Wagner took to social media as this month marks the 45th anniversary of the mysterious death of his late wife Natalie Wood.

The Rebel Without a Cause actress was 43 when she died near Santa Catalina Island in California on November 29, 1981 in what authorities said was an accidental drowning.

The boat trip had been on the couple's 60-foot yacht called the Splendour, with actor Christopher Walken and captain Dennis Davern also aboard.

Davern in 2011 reported to officials details about a conflict between Wood and Wagner prior to her death, with authorities re-launching a probe and saying in 2018 that Wagner had been 'a person of interest' in the mysterious death.

Wagner had been cleared of involvement in the death by the Los Angeles County Sheriff's Department in May of 2022.

Los Angeles County Sheriff’s Department Lieutenant Hugo Reynaga told Page Six that 'all leads in the Natalie Wood case have been exhausted, and the case remains an open, unsolved case.

'If additional leads surface in the future, which have not already been investigated, the case will be reassigned to a detective to investigate the new leads.'

Wood's daughter Natasha Gregson Wagner, who Wagner adopted following her mother's drowning, told Vanity Fair in October, 'It's just so absurd that somebody as kind and generous and loving as my stepdad has been maligned this way.'

She said of Wagner, 'I know that my dad would've done anything to protect my mom, and I think it's reckless and dangerous when people make up lies or assumptions, and they become the truth that's passed around.

'My dad is 96 and a half years old, and I don't want his legacy to be tarnished with these mistruths or untruths.'