Nahjayyah Daise was a young woman barely into adulthood when her life came to an abrupt end. The 21-year-old from Albany, New York, was in an on-again, off-again relationship and was trying to figure things out.

But she never got the chance. Police say 22-year-old Larnell Kennedy made sure of it. In a bizarre murder that authorities admit they will never have a motive for, they say Kennedy was driving with Daise as a passenger when he pulled out a pistol and shot her three times.

Kennedy pulled over and the car rolled to a stop. That's when Albany authorities said he tried to pull Daise out of the vehicle and put her in the truck -- but he dropped her. Then he got back into the vehicle and backed over her, authorities told local Albany News Channel 13.

"There's no indications that anything like this would happen," said Bob Sears, Albany's Acting Police Chief. "They did have their ups and downs in the relationship, but nothing that would ever indicate something like this would happen, so it is unusual."

Police said the couple had no known history of domestic violence.

A witness told authorities that they saw Kennedy on the roadside with the woman, and they tried to block him in. Kennedy then took off on foot, trying to cross the highway.

Security video of the incident showed Kennedy being fatally struck by a SUV, police says.

Emergency responders found Daise struggling to breathe on the side of the road. She was pronounced dead shortly after. Media reports said that Daise was killed two days before she was set to appear in Bethlehem Town Court on assault charges.