The ex-husband of former first lady Jill Biden pleaded not guilty Tuesday to charges he killed his current wife in Delaware.

William Stevenson, 77, was married to Jill Biden from 1970 to 1975.

A state grand jury this month charged Stevenson with killing Linda Stevenson, 64, who was found unresponsive at their home in Wilmington on Dec. 28. He has remained in custody since he was charged Feb. 3 with murder, unable to post the $2 million bail.

Years before his arrest, Stevenson sat down with News 12 senior reporter Tara Rosenblum for an exclusive interview - speaking candidly about his life, both of his marriages and his connection to one of the most infamous cold cases in New York history.

In that interview, Stevenson said he had a romantic affair with Kathie Durst just days before she disappeared from her Westchester home. Kathie Durst was allegedly killed by her husband, real estate heir Robert Durst, in a case that has haunted the nation for decades.

At the time, Stevenson spoke openly about his reported affection for Kathie Durst.

Stevenson was previously married to first lady Jill Biden when she was known as Jill Jacobs.

During the interview, Stevenson spoke at length about his current wife at the time, Linda Stevenson — the woman he is now accused of killing.

“I have the most amazing family,” Stevenson said in the interview. “I’ve got an amazing wife who’s going to look at this and go, ‘Wow, she really doesn’t know what really happened.’”

Stevenson described Linda as a steady presence in his life for decades and said he was open with her about his past and the difficult subject matter he was discussing on camera.

“She’s aware of everything,” he said.

He told News 12 he married Linda on Sept. 19, 1986, and spoke about helping raise her young daughter, Christina, whom he described as his closest friend. Stevenson said he and Linda had been married for more than three decades.

The latest charge against Stevenson marks a stark and jarring contrast between the man who once spoke publicly about seeking justice for a murder victim and the man now accused of committing one himself.

“One hug from her and all your worries would disappear,” her daughter, Christine Mae, wrote in a Facebook post. “The pain of losing her is paralyzing, and the emptiness in my heart is an abyss.”

Linda Stevenson ran a bookkeeping business and was described in her obituary as a family-oriented mother and grandmother and a Philadelphia Eagles fan. The obituary does not mention her husband.

Jill Biden married U.S. Sen. Joe Biden in 1977. He served as U.S. president from January 2021 to January 2025. Jill Biden’s spokesperson has said she has no comment on the Stevenson case.

Stevenson's next court hearing is set for March 16.