CHICAGO (CBS) — The two suspects charged by police for the shooting of Hadiya Pendleton both had criminal records and one of them was on probation at the time of Pendelton’s shooting, reports CBS 2′s Roseanne Tellez.

In fact, CBS 2 has learned he violated that probation three times before her killing.

18 year-old Michael Ward was put on probation after pleading guilty to a weapons charge in January of 2012, when he was still 17.

By March 28, court records show he violated that probation after an arrest for breaking into a car. On July 12, he violated probation again on a similar misdemeanor charge, and on November 26, he violated probation for a third time in less than year, when he was arrested for criminal trespass.

While all cases were eventually dropped, only one was ever reported to the judge.

CBS 2 reached the acting chief of the adult probation department, Jesus Reyes, by phone. He admits his office dropped the ball.

When asked why his third violation was not reported, Reyes said “That’s what we’re going to try to find out. From a probation stand point all three should have been reported.”

Reyes says an investigation is underway into what went wrong, but says since all three of Ward’s violations were misdemeanors, there’s no guarantee he would have been held in jail for long.

“If you look at those cases he was picked up on, they were all dismissed because why? Because the complaining witness didn’t want to follow through,” said Cook County State’s Attorney Anita Alvarez.

The other suspect in Pendleton’s killing, 20 year-old Kenneth Williams, has only one arrest on his record, a misdemeanor charge of shoplifting in 2011.

There is no computer somewhere that sends out an alert when someone on probation gets arrested, but probation officers have the job of spotting violations by routinely checking arrest records.

The head of the probation department tells CBS 2′s Roseanne Tellez that archaic computers, big caseloads and fewer officers, make the job extremely challenging.