An 18-year-old Arizona man accused of preying upon school students faces multiple counts of sexual assault, sexual conduct with a minor and other crimes.

Pinal County sheriff's deputies arrested Tyler Kost of San Tan Valley last week, accusing him of being a serial sex predator who assaulted nearly 20 students.

County Attorney Lando Voyles has scheduled a news conference Thursday on charges against Kost.

Kost was initially charged in criminal complaint last week, but Voyles spokesman Jim Knupp says Kost is now charged in a 27-count indictment issued Wednesday.

Knupp says the indictment's charges accuse Kost of sexual assault, sexual conduct with a minor and other crimes.

The previous complaint now replaced by the indictment contained similar allegations.

Kost's attorney, Christine Whalin, did not immediately respond to requests for comment.