TAYLORSVILLE, N.C. -- A prison nurse is accused of taking two pipe bombs to the Alexander Correctional Institution south of Taylorsville.

Sherry Stella Bortz, who worked for three years in the medical unit of the all-male prison, was arrested over the weekend. Investigators said they were acting on a Crime Stoppers tip that said there might be drugs inside her car when they brought out search dogs on Friday.

A dog found pipe bombs made of black powder and screws that had a birthday candle as a fuse under the driver’s seat in Bortz’s car, investigators said. The bombs were detonated by a Wilkes County bomb squad late Friday.

Investigators said Tuesday afternoon that a second Crime Stoppers tip said Bortz may have been planning to break her son out of a local jail. Her son is in the Caldwell County Jail, which is where Bortz was also placed after her arrest.

“We're not sure what the motive is. We're looking at all possibilities in the investigation, but at this point in time I couldn't say that's what the motive was or not,” said Alexander County Sheriff Chris Bowman.

Deputies searched Bortz’s home for evidence on Tuesday afternoon.

Bortz, 48, is charged with two counts of possession of weapons of mass destruction and one count of possession of a controlled substance. She’s being held on $150,000 bond.

She’ll be in court in Taylorsville on Wednesday.