Juan Castillo was found dead from a gunshot wound to the head Feb. 26.

Police have arrested a suspect in the murder investigation of an 18-year-old Santa Monica High School graduate who was shot and killed in the Pico Neighborhood Feb. 26.

Los Angeles resident Sherwin M Espinosa was arrested at his home in Baldwin Hills May 17, according to Chief Jacqueline Seabrooks, who gave a press conference on the arrest Friday afternoon.  Investigators said Espinosa, a convicted felon, had an Uzi pistol in his possession Wednesday that matches the weapon used the night of the shooting.  Espinosa is being held by the Los Angeles County Sheriff’s Office on $3 million bail as he faces charges of murder and being a felon in possession of a firearm.

The news conference revealed the first break in a case that devastated the Pico community three months ago.

“I have mixed emotions because I know justice will be done for my son but nothing can bring him back,” Castillo’s mother, Lulu, said through a Spanish language translator at the press conference.  Castillo’s father wore his son’s Samohi letterman jacket to the press conference at Virginia Avenue Park but did not speak.

Details released by detectives left just as many questions as they gave answers.

Detectives believe Castillo was sitting in a car on the 2100 block of Pico Boulevard with an acquaintance when he was allegedly shot by the 42-year-old suspect shortly before 1 a.m. early that Sunday.  Police do not have evidence that the two men knew each other and detective have not ruled out the possibility it was a random act of violence.  Neither Castillo or Espinosa have been linked to gang activity.  Lt. Saul Rodriguez told reporters drugs do not appear to be a factor in the murder either.

Officers received a call of “shots fired” in the area that night but everyone had left by the time officers got there, according to earlier reports from SMPD.

Four hours later, paramedics found Castillo lying unconscious on the street outside UCLA Medical Center on 16th Street.   The former football player had been shot in the head.  Police believe the acquaintance in the car at the time of the shooting drove Castillo to the hospital, but would not elaborate on why they believe the 18-year-old was left in the street that rainy night.

The acquaintance, who has not been publicly identified, has been interviewed by detectives but is not a suspect in the investigation.

Police believe Castillo was shot by a semi-automatic weapon similar to the Uzi allegedly found in Espinosa’s possession Wednesday.  The weapon is illegal in California under the Assault Weapons Control Act of 1989.  Forensic detectives with the SMPD are currently performing ballistics tests to see if the weapon is a match.