One of two teens charged in Kennewick murder of pregnant 20-year-old appears in court

A Kennewick teen smirked at media cameras Thursday during his first appearance in adult court for the murder of an expectant mother.

Marin J. Rivera Jr. was with a friend early May 5 in an east Kennewick neighborhood when the two confronted Andrea M. Nuñez and her boyfriend, Joseph Ayala, according to court documents.

At some point during the assault or attempted assault, Nuñez ended up shot once in the back and died at the scene, documents said.

The 20-year-old woman was 4 1/2 months pregnant with a boy.

Rivera, 17, is charged in Benton County Superior Court with second-degree murder for his alleged role in her death. Trial is set for July 8.

The charge includes the aggravating circumstance that Rivera knew the victim was pregnant at the time of the confrontation.

Being tried as an adult

Rivera’s case was bumped up to adult court automatically because of the severity of the crime and he is over age 16. He turned 17 three days before the slaying.

Co-defendant Adrian Mendoza, 17, is accused of firing the gun that killed Nuñez.

Prosecutors, in charging Mendoza with first-degree murder, say he acted with premeditated intent when he shot the woman. His trial is scheduled June 24.

Both teens are locked up in the Benton-Franklin Juvenile Detention Center on $500,000 bail.

Police have called it a gang-related killing.

Shot fired in confrontation

Mendoza and Rivera allegedly approached her “with the intent to intimidate, harass and assault (her) with a firearm.”

Nuñez’s boyfriend told police that it escalated with one of the suspects yelling “ 18th street tokers” and “Westside.” Nuñez replied with a shout of “Southside,” then fell to the ground seconds later, court documents said.

Home security cameras from a nearby apartment show the suspects around the time of the shooting as they appear to follow the couple, and then running away after the shot was fired, documents said.

Loved ones started a GoFundMe account to help with Nuñez’s funeral expenses.

This story was originally published May 16, 2019 at 7:39 PM.