MILLBRAE -- A Millbrae man suspected of molesting young relatives was arrested Wednesday on a series of charges including sex assault on a child under 14 years old.

Richard Kenneth Watterworth, 49, was arrested at his home after investigators got a tip from a family member saying he abused the children, San Mateo County Sheriff's Deputy Rebecca Rosenblatt said. The abuse had been going on for a while, but police didn't specify a duration.

Investigators also searched Watterworth's home, but didn't say if anything was seized.

Watterworth was booked into San Mateo County Jail on suspicion of child molestation, continuing abuse, oral copulation on a minor, criminal threats and brandishing a weapon.

Contact Joshua Melvin at 650-348-4335. Follow him at Twitter.com/melvinreport.