PITTSBURGH - Relatives and friends of a Pennsylvania doctor murdered on the Ohio Turnpike last month are offering a $25,000 reward for information that helps solve his killing. Meanwhile, Ohio authorities have set up a toll-free tip line.

The Ohio State Highway Patrol announced both the private fund and the hot line on Wednesday, almost three weeks after Dr. Gulam Moonda, 69, of Hermitage, was fatally shot on the Ohio Turnpike near Cleveland.

The Ohio State Highway Patrol has characterized the shooting of Moonda along the Ohio Turnpike as a crime of opportunity.

Moonda, his wife and her mother had stopped their Jaguar to change drivers when another vehicle pulled up behind, and a man got out and demanded money. After Moonda gave up his wallet, the gunman shot the doctor in the head and fled.

Neither Moonda's wife, who was in the driver's seat, nor her mother was injured. Authorities have not said how much money was taken.

Authorities in Pennsylvania and Ohio haven't charged anybody with the doctor's murder.

But part of the investigation has focused on Donna Moonda, 46, the doctor's wife, and an alleged drug dealer with whom she was allegedly having an affair. Lawyers for both have said the alleged relationship doesn't implicate them in Moonda's killing.

Two confidential informants have told authorities in Ohio and Pennsylvania that Donna Moonda met and began having an affair with 23-year-old Damian Bradford after she met him at a drug rehabilitation clinic near Pittsburgh.

The informants said Donna Moonda bought Bradford clothes, shoes and other expensive gifts and rented an apartment for him, according to police records.

One of the informants told police that Bradford said Donna Moonda was trying to divorce her husband and that she would receive as much as $4 million as part of a divorce settlement. In his will, Dr. Moonda left his wife 20 percent of his estate, the car of her choice and allowed her to live in the couple's palatial home with manicured shrubs and trees on 1.5 acres.

Authorities in Pennsylvania searched Bradford's apartment in Monaca about a week after the killing looking for Dr. Moonda's wallet, blood or other tissue as well as any evidence showing a sexual or financial relationship between Donna Moonda and Bradford, according to police records.

Police said they found three towels, a pair of sweat pants and a T-shirt with suspected blood stains in Bradford's apartment. Bradford told police the blood on the towels was from Donna Moonda's menstrual cycle and that the blood on sweat pants and shirt were his, from a motorcycle accident.

Last week, police took DNA samples from Donna Moonda. The results were still pending Wednesday.