Prosecutors filed misdemeanor manslaughter charges Tuesday against a Rohnert Park man accused of plowing his truck into a retired Sonoma State University professor on his bicycle last June.

The allegation against Robert Ernest Cowart, 69, comes in addition to a charge of felony hit-and-run in the death of environmental studies professor Steve Norwick.

Prosecutor Troye Shaffer added the charge after a review of Cowart's medical records. She would not say what in the records triggered the new criminal count, citing patient confidentiality laws. Assistant District Attorney Christine Cook said only that it was appropriate in light of the evidence.

However, Cowart's lawyers have said their client suffered a stroke at some point and may have had an aneurysm that impeded blood flow to his brain. And they have asked for a trial on his competence. It is set for May 7.

Cowart was out of custody and sitting in a wheelchair at his court appearance Monday.

Earlier this year, the District Attorney's Office received his Veterans Administration records. Criminal proceedings were suspended in the fall while the court decided if he is mentally fit to assist in his defense.

Two court-appointed psychologists have examined Cowart, but their findings have not been made public. Court records indicate both doctors have been paid by the county for their services.

Cowart faces a maximum of four years in prison if convicted. The new charge did not add to his possible jail time.

You can reach Staff Writer Paul Payne at 568-5312 or