Jill Biden's first husband Bill Stevenson says he had an affair with Robert Durst's murdered wife Kathie 10 DAYS before she vanished and thinks he's the 'missing link in the case' because real estate heir found out

Jill Biden's first husband Bill Stevenson has claimed that he may be the reason Robert Durst allegedly killed his wife Kathie in 1982 because he had an affair with her and Durst found out ten days before she vanished. 

Stevenson was married to Jill Biden between 1970 and 1975. She met Joe towards the end of their marriage when working for him when he was a Senator, and they got married in 1977 - five years before Kathie Durst vanished in 1982. 

Bill, who previously accused Jill of having an affair with Joe while he was still married to her, says he was childhood friends with Kathie. 

In an interview with Long Island's News 12 on Thursday, he claims that he and Jill hosted the Dursts at their home in 1974, before their marriage fell apart, and that Robert behaved strangely, talking to himself in the garage. 

Jill Biden has never spoken publicly of the Durst case, nor made mention of being friends with Kathie or Robert. 

Bill claimed in his interview that in 1982, after Kathie confided in him that she was scared of Robert, he spent the night with her at her New York City apartment and their friendship became intimate. 

Bill Stevenson told Long Island's News 12 on Thursday that he had an affair with Kathie Durst and slept with her ten days before she went missing in 1982. It was give years after his marriage to First Lady Jill Biden ended

This photo shows Jill and Bill Stevenson, in the 1970s, before their marriage fell apart 

Kathie and Robert Durst on their wedding day. She vanished in 1982 after telling friends she feared for her life 

Stevenson alleges that the next day, Robert showed up at the apartment 'pounding on the door' and that he slammed a wad of rolled up cash in Kathie's face. 

Ten days later, she vanished. 

He thinks Robert - who has long been accused of murdering his wife but has never been charged over it - was driven to kill her after discovering their affair.

TIMELINE OF BIDEN AND DURST MARRIAGES

1970: Jill and Bill marry

1973: Kathie and Robert Durst marry 

1974: Bill says he and Jill  hosted Robert and Kathie Durst at their home 

1974/1975: Jill and Bill separate 

1977: Jill and Joe marry 

1982: Kathie Durst disappears 

'This is something that has to be righted. I was together with them and he went crazy. I feel like I'm the missing link in this case,' he said. 

Stevenson said he watched Kathie 'grow up into a beautiful young woman' after their families became friends when they were kids. 

'She was that cool little sister - I watched her grow up to be a beautiful young woman.'

He says in 1974, he and Jill hosted Kathie and Robert Durst at their home.

He says Jill and Kathie 'hit it off'. 'Both very smart, they're similar people. At that age. It was hard not to hit it off.

'I remember him talking to himself in my garage. To me it was like, "oh my god."' 

Years later, once his marriage to Jill had broken up and after Jill and Joe had gotten married, Kathie started confiding in Stevenson, he says. 

'She said I'm having a real problem with Robert and I'm scared to death. 

She said he was being violent with her. At that point, she couldn't trust anybody around her that knew Robert. 

'I don't know why she picked me but I'm glad she did.

'But I do feel that I let her down. I look back at those last two months and go, "what could I have done differently." 

He says he visited Kathie five times between 1981 and 1982. They stayed at Kathie's apartment in New York City and it was during that time that it became romantic. 

This is the home Bill and Jill lived in in Delaware. He says that they hosted Robert and Kathie Durst there in 1974

Jill and Joe Biden in 1987, 10 years into their marriage and five years after Kathie disappeared. Jill has never made any public comment about being friends with the Dursts during her first marriage, as her ex-husband claims they were

'She was in this silk nightie. Nothing was said. She grabbed my hand, led me back to the bedroom. We closed the door and life changed for both of us. Totally unexpected. Beautiful night. No regrets. 

'The next thing I realize we hear pounding on the door, it's 7.30 in the morning, she runs out of the bedroom, runs back in and says it'd bob.

'I jumped up and ran out, he screams something and he had a wad of cash and he hit her right in the face with it. He started yelling: "Kathleen, this isn't going to happen."

She starts yelling: "I'm moving to Delaware! I'm done! We're done!' I'm like sitting there, I'm in shock. People have to understand, this guy is a monster. I saw it in his eyes.' 

Ten days later, she was reported missing. He says that he went straight to the police but no one followed up on his report. 

Robert Durst, 78, is currently on trial for murdering his friend Susan Berman in 2000. Prosecutors say he killed her to stop her from going to police and reporting what she knew about Kathie's disappearance 

'I got in my car, went to the 19th precinct - literally within 24 hours - and said: "Nuh uh. He killed her." The wrote a couple things down, and said "we'll get back to you." I never heard a word back from them.' 

Asked if he thinks he had anything to do with her killing, he says: 'Absolutely - it would have driven him crazy. I don't feel guilty about that. 

Bill last year told DailyMail.com Joe and Jill had an affair when he was still married to her in 1974 

He was abusing her and she wanted out. And I feel like if something happened wonderful at the end of her life, I hope this was it.

'I'm sorry. I just hope that you know she had the same thoughts at the end there.' 

Stevenson previously told DailyMail.com exclusively that Jill and Joe had an affair when they were still married. 

'I don't want to hurt anyone, but facts are facts and what happened, happened,' he said in August last year during Joe's campaign.

Stevenson married Jill Jacobs in 1970. 'It was February, I believe it was the 7th,' he told DailyMail.com.

Two years later, he said, the couple were working on then-New Castle County Councilman Biden's first campaign for the Senate.

At the time Biden was married to his first wife Neilia who died along with their one-year-old daughter Naomi in a car crash in 1972. 

Stevenson said he first suspected Biden and Jill were having an affair in August 1974. He was then 26, Jill was 23 and Joe was 31.

'I know exactly when it was,' he said. 'Bruce Springsteen was going to play at The Stone Balloon and I had to go to Northern New Jersey to pay him in advance.

President Biden and First Lady Jill Biden on Fourth of July. They married in 1977 - around two years after her marriage to Stevenson fell apart 

'I asked Jill to go with me and she said no — she had things to do, she had to look after Joe's kids, Beau and Hunter. It was kind of a big deal to go meet Springsteen. I had no idea she and Joe were that kind of friendly.

'Then one of her best friends told me she thought Joe and Jill were getting a little too close. I was surprised that she came to me

'That October he got confirmation. 'I was at work and a guy came in and asked: 'Do you own a brown Corvette?' I said yes, it's my wife's car.

'He said back in May it had crunched his bumper and they told him to get an estimate and he never heard back from them.

'I said: 'Wait a minute. Who is they?' And he said: 'Funnily enough, Senator Biden was driving.'

That was it as far as Stevenson was concerned.

'I asked Jill to leave the house, which she did. Her father was begging me to take her back when he found out what was going on. He asked me to give her a second chance, but I wasn't interested.

'I considered Joe a friend. I'm not surprised he fell in love with Jill. Everyone who meets Jill falls in love with her immediately. It's hard not to.'

He said last year that he had no hard feelings against Jill and thought she would make a 'great' First Lady.