Someone fatally shot Terrence Joyner Sunday as he was walking with 15-year-old Donye Thompson through a Northeast Baltimore gas station parking lot. Police know this much — they and have it on tape.

But while police don’t know the assailant who killed Joyner, 42, they recognized Thompson and have charged him with attempting to kill an unknown person. He was seen on the video tape shooting back at the assailant, according to police.

Detectives who work the Northeast Baltimore neighborhood where the shooting occurred have had “numerous, in excess of 15, encounters over the past four months” with Thompson, according to charging documents. Detectives obtained a search warrant for his home and found a green backpack containing 10 pounds of ammunition, records show.

Thompson, who turns 16 on March 22, was arrested on March 7 when he and his mother voluntarily came to the Northeast District to speak with officers, police said. He is charged with attempted first-degree murder and other charges, and on Friday was ordered held without bail by District Court Judge Catherine O’Malley, records show.

Attempts to reach relatives of Thompson were not successful. Court records did not list a defense attorney.

Joyner's killing remains unsolved. The charging documents show that Joyner was walking through the BP gas station and 7-Eleven parking lot in the 1100 block of East Coldspring Lane at about 2:30 a.m. on Sunday. The area was a short distance from Joyner's home, police said.

Joyner was walking westbound with Thompson following behind, police said. Thompson was wearing a blue “True Religion” hooded shirt, jeans and white sneakers, and investigators quickly identified him after watching earlier footage from inside the store. In the moments leading up to the shooting, Joyner and Thompson are seen quickening their pace and Joyner engages in a brief conversation with an unknown male who was “partially obscured by the range limitations of the BP security camera,” charging documents show.

The conversation between Joyner and the unknown man became heated, and the man fired a .357 handgun at Joyner that fatally wounded him, police said. As the suspect ran, Thompson is seen pulling a handgun from his waistband and firing a single shot in the man's direction. Police say Thompson's gun was a .380 caliber weapon.

A motive has not been disclosed in the shooting.

Joyner in December 2010 was charged with attempted first degree murder for allegedly stabbing someone during a fight at the same gas station parking lot where he was killed.

In that case, police said Joyner stabbed Ernest Parker several times in the chest, head and back, and confessed after being picked up by then-Deputy Major Darryl Desousa, according to charging documents from that case.

Prosecutors placed the charges on the inactive docket in August due to uncooperative witnesses, essentially suspending the case and freeing him from jail.

[This post has been updated]