She is the 33-year-old daughter of Councilman Richard Alarcon.
Andrea Alarcon is being investigated after her 11-year old daughter was found unattended at City Hall at about 11:45 p.m. Friday, where a party had earlier been held. The girl was taken to the LAPD Central Station, where her mother turned up a few hours later.
Andrea Alarcon said in a statement, "My daughter is my top priority and nothing could be more important to me than her well-being. In order for me to be the best parent possible, I have decided to seek professional help and treatment."
It was unclear what she was receiving treatment for. She was not arrested.
In December, a California Highway Patrol officer arrested Alarcon on suspicion of drunken driving. Prosecutors charged her with DUI as well as cruelty to a child because her child was in the car.
She pleaded not guilty to the charges and is due back in court again next month.
City News Service contributed to this report.
