After spending two decades thinking about Robert Durst, one would think Detective Joseph Becerra was tired of hearing that name.

"I was determined," he told us. "I wanted to see this through."

A chain of events led to the murder of Susan Berman and they all began with Durst's wife Kathie, whose body has never been recovered. Durst's motivation for killing was money and/or self-preservation. Kathie and Berman were friends and police suspect Durst told Berman what happened to his wife, so she had to be dealt with.

Durst was eventually charged with second-degree murder in the death of Kathie Durst, but prior to his arraignment, he died in a California prison. That left a bit of a hole in the heart of Detective Becerra.

"It was very frustrating," he said. "I had a glimmer of hope that he would man up and tell us where his wife's body was buried."

For him, it was of the utmost importance that they give Kathie's family closure, and without her body, that simply wasn't possible. Sadly Detective Becerra suspects Durst didn't tell anyone where Kathie's body is, but he remains hopeful that someone will come forward. One of the reasons Detective Becerra decided to take part in Blood and Money was to keep this story in the public eye.

Although Durst was eventually arrested, this case still lives rent free in Detective Becerra's soul. This is his Moby Dick.

"The time I spent on this case, over 20 years, the unanswered questions ... the fact that I couldn't give closure to her family, yeah, it still frustrates me to this day," he said.

With a deep sigh, Detective Becerra calmly said that Durst "took it to the grave with him." Thankfully, Susan Berman's loved ones knew what happened to her, but it's a small comfort.

Blood & Money airs Saturdays at 9 p.m. EST on Oxygen.