Convicted sex offender arrested after trying to get into Fairfax County school

A convicted sex offender got out of prison early and gained access to a Fairfax County elementary school Thursday. Fortunately, an automated check-in system in the school office alerted staff to his sex offender status and led to his arrest.

Police say 29-year-old Alonso Bruno Cornejo, of Vienna, tried attending a school event with a friend at Shrevewood Elementary in Falls Church Thursday. The problem is, he's not allowed within 100 feet of a school.

Cornejo -- who is a former MS-13 associate -- was convicted in 2011 of running a child prostitution ring in D.C., Maryland and Virginia, in which he sold 15-17-year-old girls for sex.

As part of his sentence, he was supposed to serve 24 years. FOX 5 hasn't been able to find out why he only served less than a third of his sentence.

A parent at the school says he's relieved the school security system did its job Thursday.

"I'm just relieved that we've got that system like you said I didn't really know that we had that but and I really wouldn't have imagined that kind of person would walk into our kid's school but they did and the system is there to protect them so it's a shame we need that system but it worked and did what it's supposed to do but yeah, I've got three kids there so I'm happy to see that system in place," said Andrew Bisson.

FOX 5 emailed the U.S. Attorney's Office for the Eastern District of Virginia about Cornejo's reduced sentence and received no response.