A St. Paul teenager pleaded guilty Tuesday to the murder of his 15-year-old friend in December.

Oscar Edwardo Cervantes, 17, originally told police Angel Reyes Hernandez was shot by rival gang members “because we are from the West Side (of St. Paul),” according to the criminal complaint filed in Ramsey County District Court.

But after police built their case, they arrested Cervantes.

The Ramsey County attorney’s office originally charged Cervantes as a juvenile. In an amended complaint filed Tuesday, he was charged as an adult with second-degree murder without intent.

Cervantes was sentenced on Tuesday to 10 years and eight months in prison. He received credit for 79 days already served.

Just after midnight on Dec. 23, Cervantes flagged down a squad car at Arlington Arkwright Park in St. Paul. He told an officer his friend had been shot in a confrontation with a group of four black males in a car.

Later, as police gathered information, they accused Cervantes of not being truthful in his accounts of how Hernandez was killed. Cervantes changed his story several times during interviews with investigators.

Authorities say Cervantes shot Hernandez in an apartment, while a young child was in the room, and then dropped his body in a parking lot near the East Side park.

A witness provided authorities with a Snapchat video sent out close to midnight on Dec. 22 of Cervantes pointing a gun at Hernandez.

On Dec. 24, another witness told authorities that Cervantes and Hernandez argued at an apartment in the 1600 block of Hammond Avenue. The witness told authorities he heard a gunshot and then Cervantes yelling that he had just shot Hernandez.

Cervantes demanded that the witness help him move Hernandez’s body, according to the complaint. They loaded the body along with a bloody couch into a vehicle. The couch was dumped into a nearby dumpster.

Then, they drove to the park where they dumped the teen’s body, according to the complaint.

Authorities say a third witness corroborated events involving the fatal shooting.