Detectives arrested 71-year-old registered sex offender Jesus Vega Jr. as a result of a sexual abuse investigation that began on Jan. 18, Livermore police Officer Steve Goard said.
The investigation determined that Vega allegedly molested a young girl at least three times over a three-month period, according to Goard.
Goard said Vega was a family friend of the victim.
Livermore police detectives concluded their investigation and presented their findings to the Alameda County District Attorney's Office on Jan. 23. The district attorney subsequently sought a warrant for Vega's arrest.
Police arrested Vega at about 4:30 p.m. that same day and took him into custody without incident.
Vega was booked into Santa Rita Jail and is being held without bail, Goard said.
His next court hearing is scheduled for Feb. 13 at the Gale-Schenone Hall of Justice in Pleasanton.
While the Livermore Police Department does not believe there are additional victims in the case, the department is encouraging anyone with more information to contact police at (925) 294-7531. Anyone wishing to remain anonymous may do so.