Derrick Thomas

March 5, 2018 – Three people who committed a home invasion robbery in Newcastle early Thursday morning were all arrested within 19 hours by Placer County Sheriff’s deputies and detectives. The two victims were unharmed.

One suspect was apprehended within an hour of the crime and the two others were arrested in Nevada County Thursday night. They were booked at the Placer County Jail on charges including home invasion robbery, kidnapping, conspiracy, assault with a firearm, and auto theft.

Arrested were Derrick Michael Thomas, 30, of Penn Valley, Lukas Mathew, 44, and Amanda Robertsen, 28, both Grass Valley area transients.

Lukas Mathew

At around 4:30 a.m. Thursday, Thomas and Mathew cut the power to a Newcastle home, then entered the occupied residence through a side garage door. Wearing masks and carrying a gun, they entered the bedroom of the male resident and held him at gunpoint. They pretended to be law enforcement officers, and said they had a warrant for the man’s arrest. One suspect found a caretaker in another room, and brought her into the man’s room, where they bound her hands.

Once the suspects gathered firearms and cash, they left. Thomas stole the victim’s vehicle and drove off. Robertsen remained outside during the robbery and drove the getaway car.

Amanda Robertsen

The victim immediately called 911, and the first deputy responding saw the victim’s car leaving the scene. By the time the deputy turned around and caught up, the victim’s car had been driven off a hill and abandoned. Thomas was found in the area within an hour and arrested.

Our Crimes Against Persons detectives took over the investigation, which quickly led them to Nevada County, where they arrested Mathew and Robertsen separately.

Bail for Thomas is set at $2.15 million, Mathew’s bail is set at $2.3 million, and Robertsen’s is set at $200,000.