A 17-year-old boy pleaded no contest to voluntary manslaughter Monday for his role in the brazen daytime robbery and fatal shooting of a gardener in Oakland's Fruitvale District last year.

James Lee Allen's plea calls for him to receive a 12-year state prison term when he's sentenced by Alameda County Superior Court Judge Carrie Panetta on Jan. 3.

Allen, who faced a murder charge before he entered his plea, was one of four teenagers who were arrested in connection with the robbery and death of 42-year-old Antonio Torres while Torres was working in the front yard of a client's home in the 1600 block of 34th Avenue at about 1 p.m. on May 20, 2011.

Oakland police said the teens targeted Torres because they wanted to steal his gold necklace and his iPod.

The Alameda County District Attorney's Office initially charged Allen and two other suspects as juveniles and one suspect as an adult.

But prosecutors recently charged Allen and Jonathan Laverne Johnson, who was 17 at the time of the incident but is now 18, as adults.

Johnson, who is accused of being the person who fatally shot Torres, pleaded not guilty today to murder and a special circumstance allegation that he committed a murder during the course of a robbery. He's scheduled to have a preliminary hearing on Dec. 10.

Alameda County District Attorney spokeswoman Teresa Drenick said Johnson and the other three teens "walked around hunting for someone to rob." She said they all intended to commit an armed robbery and the other three teens "all knew Johnson had his loaded black revolver."

Drenick said Johnson is accused of killing Torres by firing two or three shots at him, striking him in the back.

She said Torres "was a completely innocent man" who had been working as a gardener at his client's home for 25 years.

Drenick said Johnson is "the only remaining defendant" in the case but did not say what the outcome was of the cases against the man who was charged as an adult last year and the other suspect who originally was charged as a juvenile.

The man who was charged as an adult last year, when he was 19, is now out of custody but appeared in court briefly today. Panetta ordered him to return to court on Dec. 10 to be a prosecution witness in Johnson's hearing.

Drenick said Torres' family members are expected to comment on how his death has affected them when Allen is sentenced on Jan. 3.

Dressed in a blue sweatshirt, tan slacks and tennis shoes, Allen appeared to be nervous when he entered his plea today. His mother was present for his hearing.

In announcing the arrests of the four suspects in September 2011, Oakland Police Chief Howard Jordan, who was the department's assistant chief at the time, said people wearing gold necklaces and chains had been the target of numerous crimes in the prior six months because the price of gold had soared and stealing gold items had become "a lucrative business."

Jordan warned people to "be vigilant" and pay attention to their surroundings if they wear gold items.