SEATTLE -

King County prosecutors say a Seattle-area man accused of draining more than $330,000 from his 86-year-old grandmother's savings through threats, lies and forgery has been charged in the case.

Seattlepi.com reports that prosecutors say 29-year-old Derek Bischoff of Burien told his grandmother he needed the money to pay drug debts and bribe crooked law enforcement officers. They say he really used it to pay for prescription painkillers and prostitutes.

In court papers, a King County sheriff's detective says Bischoff had been conning his grandmother for a year before his mother turned him in earlier this month.

Bischoff has been charged with one count of first-degree theft and nine counts of forgery. He also faces a misdemeanor assault charge related to allegations that he attacked his grandmother. He was booked into the King County Jail this week.