A black man whose death in police custody triggered two nights of rock- and bottle-throwing may have suffocated while lying tied and handcuffed in a patrol car, medical investigators said Friday.

Edgar Allen Price, 40, of Houston died after a struggle with police Wednesday night as eight officers tried to arrest the 6-foot-3, 300-pound drug suspect.Dr. Charles Diggs, assistant Hillsborough County medical examiner, said that from tests so far it appears Price suffocated.

"He is working it as an asphyxiated death," said April Strouse, a medical investigator in the medical examiner's office. "But we don't know how. We have not been able to determine that yet. There is a very intense investigation going on."

She said doctors hope to have conclusive results by next week.

Diggs said officials were looking at the possibility that Price was in the cruiser when his breathing stopped, adding that he had been deprived of oxygen for some time.

Price's death triggered violence Wednesday and, to a lesser extent, Thursday night in College Hill, an economically depressed, predominantly black neighborhood. One person was arrested Wednesday night and nine Thursday night.

There were no disturbances Friday night, and police said that no sections of the area were blocked off.

The breathing of a person who is intoxicated or stunned, then placed face down in handcuffs on a seat or car floor, can be restricted, Diggs said. Price reportedly had alcohol in his blood.

But Strouse, who wouldn't confirm whether tests showed Price had been drinking, cautioned, "There are a lot of things that can cause restricted breathing, and we have to wait until we know for sure."

Deputy Chief Thomas DePolis had said Thursday that preliminary findings showed Price died of a cardiac arrest, but that authorities had not yet determined what caused Price's heart to stop. The findings showed police did not choke or beat Price during the confrontation.