(CNN) When Aaron Fraser began excavating behind his childhood home in Jacksonville, Florida, as part of a renovation in 2014, he made a gruesome discovery: human remains.

They were the skull and bones of his mother, Bonnie Haim, who had gone missing in January 1993 and whose body had not been found.

Prosecutors say that discovery led officials to arrest her then-husband, Michael Haim, and charge him with second-degree murder.

"The truth was always out there, buried in their backyard," Assistant State Attorney Alan Mizrahi said in opening statements in the murder trial on Tuesday.

Michael and Bonnie Haim had been having marital problems, and he has long been a prime suspect in the case, his defense attorney Janis Warren said in her opening remarks.

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