Updated

Police are trying to determine if the two Washington-area sniper suspects charged in a Sept. 21 shooting death in Montgomery had help from a third person, possibly driving a getaway car.

Police Sgt. Scott Martino said Monday investigators are looking into the possibility that a blue car that got in the way as a police officer chased one of the suspects may have been driven by an accomplice of John Allen Muhammad and John Lee Malvo.

"We originally thought it might have just been someone that was in the wrong place at the wrong time," Martino said.

Montgomery Mayor Bobby Bright said investigators began considering the blue car "in a different light" when they heard a Michigan man had been arrested as a material witness in the sniper case.

"A third guy could answer a lot of unanswered questions about what happened that night," Bright said.

Muhammad, 41, and Malvo, 17, were charged with capital murder last week in the Montgomery shooting that killed one woman and critically wounded another outside the liquor store where they worked. Police said a fingerprint, identified as Malvo's, was on a weapons publication found at the scene, and an officer identified Muhammad from a photo lineup as the gunman who ran.

Martino said Montgomery police are now working with the sniper task force to make sure a man arrested in Michigan on Saturday is also questioned about whether he has any knowledge concerning the Montgomery shooting.

The material witness, Nathaniel O. Osbourne, was co-owner of the 1990 Chevy in which Muhammad and Malvo were arrested Thursday at a rest stop near Frederick, Md.

Martino said a blue car pulled out from behind a fast-food restaurant across the street from the liquor store as Officer Dwight Johnson was chasing a suspect on foot. Johnson has identified Muhammad as the man he saw standing over the victims of the shooting just after the shots were fired.

Police said Johnson ran after the man and came within a few feet of him, but the chase was interrupted when the blue car pulled in front of the officer and the suspect put his hand on the car to keep from being hit.

At the time, police put out a news release asking the driver of the blue car to come forward as a witness.

"We were first interested because we thought his fingerprints might be on it," Martino said.

At the same time that Johnson was chasing the suspect believed to be Muhammad, a witness was chasing another suspect, believed to be Malvo, Martino said. He said investigators believe Malvo was standing near a drainage ditch between the liquor store and a gas station at the time of the shootings.

Montgomery Police Chief John Wilson has said he believes Muhammad fired the shots that killed Claudine Parker, 52, and seriously injured Kellie Adams, 24.

Martino said neither suspect was actually seen getting into the blue car or any other vehicle following the shootings.