RENO, Nev. (AP) — A 66-year-old Reno man who police say was driving an SUV that plowed through a house where two children died has had his driver’s license suspended six times since 2002, but none of the suspensions stemmed from criminal convictions, state records obtained Wednesday show.

Reno police were investigating whether Sheldon Berg had a medical event before his Subaru crashed into the home on Monday. A 2-year-old boy and 4-year-old girl were killed.

The names of the children who lived in the modest neighborhood near downtown have not been released.

No charges have been filed, and police said they do not believe drugs or alcohol were involved.

Berg has an active, restricted license issued in March that doesn’t expire until April 2019, although it requires an annual doctor’s note.

He has been required to submit letters from a doctor certifying his ability to drive at least since 2013, when he was involved in an accident after suffering a medical episode, according to the Nevada Department of Motor Vehicles. Police said Berg struck two unoccupied vehicles and was the only one injured.

His license was taken away on March 6, 2013, and suspended about 12 weeks before being reinstated. The records provided to The Associated Press show he failed to submit to an examination in that case.

Berg has been under a doctor’s care for a medical condition, according to his mother who declined to elaborate.

Mary Ellyn Berg of Santa Rosa, California, also said her son was still hospitalized when a Reno nurse called her Tuesday night to give her an update. She said she hasn’t seen him in at least a year and that he’s single and does not have relatives in Reno to care for him.

“He sounds OK,” the mother said

Reno police spokesman Tim Broadway said he believes Berg has contacted a lawyer, but no attorney has spoken to police yet.

Berg has faced a total of six suspensions since 2002. In 2010 and 2011, it was due to a failure to comply with a restriction. In 2007, his license was voluntarily canceled for about a month before being reinstated with a physician or specialist report recommended. There was another suspension in 2004.

In each case, Berg followed the proper steps to re-obtain the license, the records show. The specific cause for the individual suspensions was not immediately clear, but Berg had no convictions on file.

DMV spokesman David Fierro said it’s up to law enforcement to determine when driving privileges are taken away. When police require an annual medical letter, the driver takes it in to be reviewed at the DMV, which is usually accepted at face value.

The official form to be completed by a doctor asks for the patient’s diagnosis, status of the condition and treatment, including medication, and if that condition and treatment will affect the patient’s ability to drive.

DMV officials can also request a doctor’s note anytime a driver renews a license, which is done every eight years or every four years for those over age 65.

“We try to be diligent in identifying people who we may need to have a doctor look at them and confirm,” Fierro said.