PHOENIX (AP) _ A convicted sex offender who disappeared for a week with two children of an immigrant family has been accused of sexually molesting them and their sister for three months before the disappearance.

Marlin Eugene ''Marty'' Price, 27, was charged with 19 counts of sexual conduct with a minor, one count of sexual abuse and two counts of custodial interference. The indictment was handed up Friday and unsealed Monday.

A 14-year-old boy and a 12-year-old girl were found April 21 at a motel in Eagle Rock, Mo., after a nationwide search. They had been camping in a nearby national forest with Price, who was arrested the same day.

While the children were missing, their parents, Mary and Gabriel Mathews, told reporters the family had befriended Price in August while living in Reno, Nev., and planned to take him back with them to Ireland.

The indictment said Price molested the two children and their 15-year-old sister between Jan. 20 and April 14, the date Price and the two children disappeared.

One count accused Price of directing the 15-year-old and the 14-year-old to have sex with each other.

Another count against Price said the children's father ''walked in'' on Price having sexual intercourse with the 12-year-old. But Cpl. Mitch Kelsey, the Glendale police spokesman, said investigators told him the parents didn't know about the alleged molestation.

The parents said after the children disappeared that they had given Price $1,000 to help him with moving expenses and that they didn't know of his 1984 conviction in Houston of sexual indecency with a minor.

There is no telephone listing for the Mathews family and they couldn't be located for comment Tuesday.