PORTLAND (AP) – Cumberland County sheriff’s investigators are reviewing an apparent drug overdose by a 22-year-old jail inmate being held on attempted murder charges for shooting at two policemen in South Portland.

Cumberland County Jail officials said Terrell Dubois was found unresponsive in his maximum security cell on New Year’s Day.

After Dubois was taken to a hospital, officials said a toxicology screen indicated he may have overdosed on an anti-psychotic medication he was on.

Jail officials are trying to determine how he got enough of the drug to cause an overdose.

Dubois was charged with two counts of aggravated attempted murder after he opened fire on officers who were trying to arrest him in 2006 in South Portland.

Both Dubois and a South Portland officer were hit multiple times.