FARRELL, Pa. -- DNA samples from the widow of a western Pennsylvania doctor are being requested as part of a murder investigation by Ohio Highway Patrol, according to court papers.

Dr. Gulam Moonda, 65, of Hermitage, Mercer County, was killed May 13 on the Ohio Turnpike. Donna Moonda said an unknown man robbed and shot her husband while she had their car pulled over to change drivers, according to a police report.

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Donna Moonda has not been named a suspect, but an affidavit of probable cause filed Thursday night says that investigators want swabs of saliva from her mouth.

The woman's samples will be compared with suspected blood stains on clothing and towels that were removed this week from the Center Township apartment of her alleged boyfriend, Damian Bradford, according to the affidavit.

Bradford says the confiscated items became stained during both Donna Moonda’s menstrual cycle and a traffic accident, according to the affidavit.

Bradford is being called a "person of interest” but police have not said he is a suspect. He’s being held in jail on unrelated drug charges and a parole violation.