Authorities in North Carolina are investigating a burglary at the home of Greg Biffle, the recently deceased former NASCAR star, who was killed along with six other people in a plane crash last month.

An incident report from the Iredell County Sheriff’s Office reveals that a break-in occurred at Biffle’s residence in Mooresville on January 8.

On Wednesday, Sheriff Darren Campbell announced that a burglar had entered a safe inside the home. Among the items taken from the house were $30,000 in cash, guns, memorabilia, and a backpack.

“We’re working the case,” Campbell said. We are waiting on some digital evidence.”

The sheriff says they are conducting interviews, but no arrests have been made.

Biffle, his wife, and two children were killed in a plane crash on December 18 when their aircraft attempted to return to Statesville airport mere minutes after taking off from that exact location.

The aircraft hit the ground just short of the runway, resulting in an enormous fireball that consumed the aircraft, killed the Biffles, and three other people. The incident is under federal investigation, and no cause for the crash has been publicly released.

Authorities have revealed that three people on board the plane, including Biffle, held pilot licenses. Though officials admit they do not know who was flying the aircraft at the time of the crash.

A public memorial for Biffle and the other six crash victims is scheduled for Friday in Charlotte.