BROWARD COUNTY, Fla. -- The man accused of fatally shooting three men on consecutive Friday nights in February to go on a shopping spree will be formally charged later this week with the robbery of two more victims, police said.

Police records allege that two weeks before the fatal shootings, Brian Bethell robbed two doctors from New York at gunpoint in Hollywood. Bethell allegedly bumped his car with theirs and stole their wallet and jewelry when they got out to inspect the damage.

At his arraignment Monday, Bethell pleaded not guilty to shooting Angel Medina, the first of the three men Bethell is accused of murdering.

Investigators said Bethell confessed to killing Frederick Gunther, Albert Avenaim and Medina shortly after he was arrested at his Margate home.

Gunther, 76, was fatally shot in the chest as he got out of his car to pick up his girlfriend, Angeline Hartwick, from her Plantation home.

Police said it was one in a string of Friday night shootings by Bethell that began Feb. 3, when Medina, 41, was shot and killed.

Detectives said ballistics tests show that the bullet used to shoot Medina was fired from the same gun that was used in Avenaim's shooting.

Avenaim, 63, was shot behind Padrino's Cuban Cuisine on the night of Feb. 10 after dropping his wife off in the front of the restaurant and driving around back to look for a parking spot, police said.

Investigators said shortly after Gunther's death, Bethell used Gunther's credit card at the same Wal-Mart where Avenaim's credit card was used the night he was shot. A store employee recognized the couple, followed them to their car and reported their license plate, police said.

His girlfriend, Natasha Edwards, was also arrested and charged with accessory to armed robbery, credit card fraud and grand theft.

Bethell is being held without bond at the Broward County jail.