North Haverhill — A 58-year-old Lebanon man who is a registered sex offender pleaded guilty this week to 40 counts of possessing child sexual abuse images.

John Laybourne was sentenced to 5½ to 11 years in New Hampshire State Prison, Lebanon police said in a news release.

The case started in July, when Lebanon police received a complaint that a sex offender was in possession of child pornography. Authorities executed a search warrant at a Hanover Street residence and on several electronic devices located “very graphic” images, police said.

Laybourne is a Tier 3 sex offender, meaning he must register for life. In the 1990s, he was convicted of aggravated felonious sexual assault on a victim under the age of 13, according to the state registry system.