The man accused of killing one man and wounding another by opening fire n a Fairfax County barbershop last year has an IQ of 66 and likely did not understand the implications of waiving his Miranda rights and talking to police, a defense expert testified Tuesday.

Hung Nguyen (Courtesy Fairfax County police)

Clinical psychologist William Ling testified that Nguyen, 44, of Annandale, had the level of cognitive functioning of someone normally considered “disabled or mentally retarded.” He said the Vietnamese immigrant’s diminished capacity was likely the result of head injuries suffered during a car accident in his homeland.

“It’s whether or not he understood the right and the consequences of waiving [his Miranda rights],” said Deputy Public Defender Dawn Butorac.

Nguyen was charged with killing barber Le D. Hoang, 39, of the Alexandria section of Fairfax County, and is facing additional charges for wounding an unnamed 38-year-old co-worker. Nguyen once worked at the barbershop in the 1600 block of Belle View Boulevard and police allege the shooting was the result of a dispute between employees.

At the hearing Tuesday, Fairfax County police officer Michael Porter testified that Nguyen showed up at the Sully District police station with three friends and turned himself in around 11 p.m. on April 13, the day of the shooting.

“’I shot someone,’” Porter recalled Nguyen saying.

Porter testified Nguyen repeatedly said “they hurt me,” but the officer said it was unclear who Nguyen was referring to. Nguyen gave a statement to detectives later that night, but it has not been made public.

Deputy Commonwealth’s Attorney Katherine E. Stott argued Nguyen was fully aware of what he was doing that night and his statement should be part of the trial.

“The defendant on his own recognized he had done something illegal and knew to turn himself in,” Stott said.

Circuit Court Judge Michael F. Devine said he would rule on the motion to suppress Nguyen’s statement before the next scheduled hearing in the case on Feb. 13.