Branded a "predatory pedophile" by authorities, a former Boise school bus driver convicted of molesting children was sentenced to up to 21 years in prison.

Steven Dean Ransom, 38, must spend at least seven years behind bars before becoming eligible for parole.On Friday, 4th District Judge Alan Schwartzman ruled out a defense request for a 120-day psychological review that could possibly have led to Ransom's release on probation.

The judge said the defendant's steadfast denial of guilt makes him "a significant risk" to repeat the offense.

Ransom's attorney, Gordon Nielson, said he plans to appeal the conviction and sentence.

Following an eight-day trial, an Ada County jury convicted Ransom on March 1 of one count of lewd and lascivious conduct and one count of child sexual abuse. The molestation involved two girls between 1987 and 1990.

One of the victims was a 12- year-old relative, and the other was a 10-year-old developmentally disabled student attending special-education classes, authorities said.

Ransom was employed for 10 years as a school-bus driver, transporting children to and from Boise public schools, until he was fired last spring. During court testimony, prosecutors alleged he befriended children during bus rides, then molested them.

Deputy Prosecutor LaMont Anderson said Ransom would frequently take developmentally disabled children on fishing outings or buy them "trinkets," only to later molest them.

"This man is a predatory pedophile, and he picks the most vulnerable victims," Anderson said.

The defense appealed for leniency, noting that Ransom had no prior criminal record, has a record of distinguished service in the military and retains the strong support of friends and family.