DNA samples collected from the body of a Potomac woman killed this month at her home show that an unidentified male came into close contact with Shohreh Seyed-Makki before she was slain Oct. 6, a law enforcement official said.

Mark K. Makki, 23, her only son, is charged with first-degree murder and robbery in the slaying.

A law enforcement source close to the investigation said traces of the unidentified man's hair were found on the back of the victim's hands, and bodily fluid belonging to the same man -- possibly saliva or sweat -- was gathered from her neck area. The source asked not to be identified because the investigation is open.

The source said investigators believe the homicide was not a random act of violence. Relatives said police told them there were no signs of forced entry at the residence.

Police arrested Makki three days after the crime and said he had a long-standing feud with his mother over his girlfriend, Aramis Mizani, whom the mother disliked.

Makki was released on $250,000 bond Oct. 13 after prosecutors acknowledged that DNA tests conducted in the case did not link him to his mother's body at the time of the homicide.

Makki's arrest angered his relatives and friends, who have described the suspect as a nonviolent young man who loved his mother. They say he is innocent.

Makki's defense attorney, Bruce Marcus, would not comment yesterday.

Police have declined to elaborate on the possible motive in the case. Prosecutors have said they still have probable cause that implicates Makki in his mother's slaying, despite the emergence of exculpatory evidence.

Police said in a charging document that Makki lied to detectives about his whereabouts the day of the crime, had an unexplained fresh wound and possessed an empty envelope believed to have contained cash that belonged to his mother.

Makki, who surrendered his passport to authorities when he was released on bail, has a preliminary hearing scheduled for Friday.