Alameda County Board of Supervisor Nadia Lockyer said on Friday she would resign.
The embattled Lockyer told her colleagues in a letter that she planned to step down from her office.
Lockyer, who has been in a substance abuse treatment program, said she is not able to be a good mother to her child and represent her 325,000 constituents in District 2 "while also trudging the waters of early recovery from addiction and the aftermath of interpersonal violence."
Lockyer, 40, who is married to California Treasurer Bill Lockyer, apparently is referring to an incident at a motel in Newark on Feb. 3 in which she alleged that an ex-boyfriend assaulted her.
The Alameda County District Attorney's Office initially investigated her allegations but then turned the probe over to the California Attorney General's Office because Lockyer formerly worked for an agency connected to the district attorney's office.
Before she was elected to the Board of Supervisors in November 2010, Lockyer worked for the Alameda County Family Justice Center, an agency in which the district attorney's office and other county departments work together to provide a variety of services to victims of domestic violence, child abuse, elder abuse and sexual abuse and exploitation.
Her District 2 seat encompasses Hayward, Newark and Union City and parts of Fremont and Sunol.
Lockyer announced Feb. 14 that she was at a wellness and recovery center.
According to her chief of staff, Ruben Briones, Lockyer missed six regular board meetings and several board retreats while she was in the treatment program.
On March 20, Lockyer participated in her first board retreat in many weeks and on March 27 she participated in her first regular board meeting in weeks. Lockyer has regularly participated in board meetings since then.
In her letter, Lockyer said, "In Alcoholics Anonymous and Narcotics Anonymous, days of sobriety are counted. In motherhood, the number of days with a healthy level of stress and tears should be too."
She said, "While I can boast 77 days of sobriety to this day, I can barely count to 10 in the latter category."
Lockyer said, "For this, I owe my family, constituents, staff and colleagues a huge apology. Reality is, I set my personal goals in recovery too high and too quickly. I got myself in a place called addiction all by myself."