An Upper Darby teen accused of opening fire in a crowded bowling alley last year, shooting five people and killing one, has asked a judge to transfer his first-degree murder case to juvenile court in Montgomery County.

Ahead of that hearing, scheduled for Feb. 22, attorneys on both sides have filed dueling motions, portraying Jamel Barnwell, 18, alternatively as a developmentally impaired teen and a violent criminal.

Lawyers for Barnwell say he has a low IQ and contend that because the shooting took place when he was 17, he should be held less responsible for his actions than an adult. They further argue that Barnwell shot Frank Wade, 29, in self-defense after being attacked by a group of men inside the Our Town Bowling Alley in East Norriton.

“The law is clear, juveniles are different and those differences make them less culpable and more likely to be rehabilitated and amenable to treatment,” attorney Carrie Allman wrote in a petition urging the judge to transfer the case to juvenile court, where Barnwell would face lesser penalties if found to have committed the crime.

But prosecutors, led by Assistant District Attorney Samantha Cauffman, dispute Allman’s characterization of the case and have asked County Court Judge William Carpenter to try Barnwell as an adult.

“There is nothing mitigating about shooting five individuals in a crowded public bowling alley and subsequently finishing off the only one of the five that was unable to turn and flee,” Cauffman wrote, calling the incident “a horrific mass shooting.”

Surveillance footage recorded inside the bowling alley and played during Barnwell’s preliminary hearing showed one of Barnwell’s friends bumping into another man. The two got into an argument before a woman pulled the man away, and Barnwell’s group continued walking.

About two minutes later, a larger group of men, including Wade, approached Barnwell’s group, the video showed. The two groups began fighting almost immediately, and during the melee, Barnwell pulled out a handgun and fired, causing the rest of the group to run and the dozens of other patrons in the bowling alley to duck for cover.

Barnwell saw Wade crawling on the floor and continued to shoot him until he ran out of bullets, killing him, the video shows. Barnwell then fled with his friends, and later surrendered to police.

Cauffman noted that Barnwell was just three months shy of his 18th birthday at the time of the shooting and took the deliberate, premeditated step of bringing an illegal semiautomatic handgun with him into a public place. Barnwell fired 15 shots inside the bowling alley, even though no one else involved in the fight that sparked the shooting was armed, according to investigators.

Prosecutors said Barnwell has a history of juvenile arrests in his native Delaware County and has “come back each time like a boomerang” with additional arrests after serving the sentences mandated by the courts.

Allman, in her petition, did not dispute that criminal history. But she said Barnwell, after earlier arrests, had not received appropriate rehabilitative and educational services. Allowing the case to proceed in adult court, she said, would subject Barnwell to a possible sentence of life in prison and prevent him from receiving the help he needs.

“These factors all show that an environment that would support his educational, social and adaptive learning needs is appropriate and necessary,’' Allman said, “and adult prison is not that place.”