A prosecutor told jurors Monday that there was sufficient evidence for them to convict a suspected gang member of murdering a 17-year-old student at Castlemont Leadership Preparatory High School in Oakland in May shortly before the victim was to graduate.

Alameda County Deputy District Attorney Eric Swalwell said Tuesday that Michael Heartsman, 22, killed Ditiyan Franklin Jr. in the 2400 block of Ritchie St. at about 2:25 p.m. on May 25 as part of a long-running gang feud.

Franklin, who was a senior, was scheduled to graduate a few weeks later.

In the aftermath of Franklin’s death, Oakland Unified School District officials described him as well-liked and responsible, with a record of never having  been disciplined at school.

However, Swalwell said that Franklin belonged to a gang called the Taliban Mafia. He said Heartsman belongs to the rival Case Boys gang and has gang tattoos.

The prosecutor said Hearstman "coldly executed" Franklin as he rode his bicycle near the corner of Olive and Ritchie streets, near Arroyo Viejo Park.

Swalwell said Heartsman first shot Franklin in the arm and then "finished him off" by shooting him a second time in the side in a driveway about 20 yards away as Franklin fled.

He told jurors Monday that they should believe the testimony of Lionel Harris, whom he said was also a member of the Taliban Mafia and was riding on the handlebars of Franklin's bike during the shooting. Harris identified Heartsman as the shooter.

Swalwell said that although Harris "is not an angel," his testimony was corroborated by other evidence in the case, such as the autopsy and cellphone records that place Heartsman in the area where the shooting occurred.

Heartsman's attorney, Gregory Martin, told jurors in his opening statement that Heartsman wasn't at the scene of the shooting and played a video in court last week that he said proves Heartsman was elsewhere. Martin was expected to give his closing argument later Monday.