Petaluma police arrested a woman on suspicion of grand theft from an elder person at the Marin County Jail last week, after she was picked up on unrelated theft charges.

Police Lt. Tim Lyons said that in early January detectives took a report from a 75-year-old Petaluma dementia patient who claimed that 28-year-old Tatiana Williams had been taking money out of her bank account without her permission.

The investigation led to video surveillance footage of Williams using the victim's ATM card at a Qwickstop market in December.

Then, on Jan. 14, Petaluma detectives found out that Williams had been arrested on unrelated charges stemming from a different theft case in Marin County. They arrested her on charges of grand theft, theft of an elder person and violation of probation.

Williams was denied bail and booked into Sonoma County jail.