"The victim told responding sheriff's deputies and Los Gatos police that Foster dragged her by her hair, physically threw her out of the house, and punched her in the head 8 to 10 times", read the DA's release.
Foster was a first-round draft pick last April out of Alabama, and although injuries hindered the start of his rookie season, he did win NFL Defensive Rookie of the Month in December and finished as the team's second-leading tackler.
"Rueben Foster will not participate in team activities as he is tending to his legal matters", the statement said. He is scheduled to meet with the team this week, a sitdown that could determine his future with the franchise. Foster was initially facing one misdemeanor count of possession of a large capacity magazine, but prosecutors dropped the charge Monday in light of a higher court injunction prohibiting the enforcement of the charge.
Foster has spent time this offseason working out at the Niners' facility on his own but will not be joining the rest of his teammates as they start the offseason program.
The charges stem from an incident on February 11, when the Los Gatos-Monte Sereno Police Department responded to a possible disturbance at a Los Gatos home and ended up arresting Foster.
The DA's office said Friday it is prepared to prosecute Foster even if the reported victim ends up not testifying, an issue that stymied previous domestic-violence cases against players. Foster didn't enter a plea at his arraignment before Santa Clara Superior Court Judge Nona Klippen at the Hall of Justice in San Jose, California, and he left the courthouse after Klippen set his bail at $75,000.
When fullback Bruce Miller was in the midst of legal woes stemming from a domestic incident in 2015, he stayed away from the offseason program; Miller was released prior to the 2016 season after a different arrest for assault.
The 49ers called the domestic violence charges against Foster disturbing. In a statement, the 49ers organizations said: "We will continue to follow this serious matter".
"We don't condone this kind of behavior and certainly would not like to see any of our players have any of these kinds of issues or the victims to suffer any at all".
The NFL has said it is monitoring the Foster case but has made no announcement of any penalties or suspensions for the second-year player.