BURLINGTON — A 43-year-old Vermont sex offender is going to prison for 27 months for failing to register as a sex offender.

Vermont’s federal prosecutor said William Robertson of Burlington received the sentenced after he pleaded guilty to one count of violating the Sex Offender Registration and Notification Act.

Court records said Robertson served 10 years in prison for sexual assault on a minor female. He lived in Florida and South Carolina for two years before moving to Vermont a year ago, but he didn’t register as a sex offender until July of last year.

Robertson could have been sentenced to up to 10 years in prison.