MESA, Ariz. -- A 20-year-old Mesa man faces manslaughter charges after falsifying a story in the wake of a shooting on April 29, police said.

Efren Chavez-Rivera was initially booked on charges of aggravated assault, misconduct involving weapons, and discharging a firearm within city limits after the late-night shooting Tuesday at an apartment in west Mesa.

The victim, who suffered a chest wound, died May 6.

Police said they received a call at 10:52 p.m. from medical staff at Mesa General Hospital after Chavez-Rivera and the victim, Antonio Quintana-Hernandez, 27, were dropped off at the emergency room entrance.

The victim had an apparent gunshot wound to his chest and received immediate medical attention, said Detective Chris Arvayo. He was then transported to a local trauma center via air ambulance, where he has been listed in critical condition.

The victim told investigators that he had entered his apartment shortly before 11 p.m. when he heard a loud bang and felt a sharp pain in his chest, according to Arvayo.

Realizing that he had just been shot, the victim fled his apartment on foot and made his way to Broadway Road to find a ride to the hospital, Arvayo said.

The victim told investigators that he did not know who had shot him.

Officers went to the victim's apartment and found evidence that a shooting had occurred.

Chavez-Rivera initially told investigators that he had found the victim along Broadway Road and had stopped to help him, Arvayo said.

He said that he helped the victim find a ride to the hospital, according to police.

After further questioning, investigators said they discovered that the suspect and victim were in fact roommates.

Chavez-Rivera said that he had found a bag containing several handguns and brought the guns home with him. He said he started to play with one of the guns in front of Quintana-Hernandez, at which point he accidentally shot him in the chest, according to Arvayo.

After the shooting occurred, Chavez-Rivera said he assisted the victim in locating a ride to the hospital.

He told investigators that on the way to the hospital, he threw the guns into a Dumpster at a local convenience store. Investigators said they were able to locate two of the guns there and discovered that one of those guns had been reported stolen.