OAKLAND — A fourth man charged with murder in the fatal shooting of a 30-year-old mother during a gunbattle last month in West Oakland admitted to police he gave an assault rifle to one of the gunmen, according to court records released Wednesday.

Michael Stills, 21, is the third of the four men charged to admit being present at the gunfight that led to the death of Chyemil Pierce on March 9 in the 2800 block of Chestnut Street, according to the court documents. He was scheduled to enter a plea to the charge Wednesday.

Police had previously said that the first suspect charged in the case, Anthony Sims, 19, had admitted his involvement. The new court documents state that Shelton McDaniels, 29, who was arrested March 13, has also admitted being involved in the shooting. McDaniels has been charged with murder and other crimes related to the shooting.

A fourth suspect who has been charged with murder and other counts in the case, Jerry Hardin Jr., 29, who was arrested with McDaniels, apparently made no statements to police.

Stills was initially arrested March 26 on suspicion of being an accessory, but was charged Monday with murder.

In a probable cause statement in support of Stills” arrest, Sgt. Michael Cardoza wrote that Stills was identified by witnesses as being present at the gunfight and admitted “being on scene and possessing an assault rifle, which he handed off to another shooter, who then used the weapon to fire several rounds from it.”

The name of the person whom Stills gave the rifle to has not been released. It was not known until court documents were released that an assault rifle had been used in the gunbattle.

Even though Stills did not fire a gun, under the law he was charged with murder because of his participation in the gunbattle that led to Pierce”s death.

Pierce, the mother of three children who worked at the human resources department of Kaiser Permanente, had just gotten out of the car with two of her children, ages 7 and 9, and was walking to her home when the gunfire erupted. She was shepherding her children to safety when she was shot in the head. None of the four men charged have said that they knew Pierce.

The deadly violence that killed Pierce, and left Sims and a 16-year-old boy wounded, happened after a physical fight between two groups of women on Chestnut Street. It escalated when one of the women was hit by a man. Sims and the 16-year-old were called to come to the scene from another part of West Oakland. McDaniels, Harbin and Stills as well as others were already there and the gunbattle soon started.

Police have said members of two West Oakland gangs were involved and that several guns have been recovered.

Sims was arrested at Highland Hospital on March 10. His attorney has said he was only trying to protect the 16-year-old.

Police have not said what role was played by the 16-year-old, who is still hospitalized, but have said more arrests are expected.