SAN ANTONIO -- A protective order and an electronic monitoring device did not protect Eva Irene O'Connor from the ex-husband she reportedly feared.

Matthew O'Connor was supposed to appear in court Wednesday on charges of violating a restraining order but instead allegedly shot and killed Eva Irene before he turned the gun on himself, police said.

But what many don't know is that on the morning that O'Connor allegedly shot his ex-wife, he was wearing an electronic monitoring device around his ankle.

"The device was plugged into the defendant's home phone, and the defendant was wearing his ankle transmitter," said bond officer Leticia Moreno. "If the defendant leaves the house then it records that, and when he comes back into the house, it will record that as well."

Officials said they believe O'Connor had his ex-wife's slaying all planned out.

"What we thought was that he was leaving his house for work -- an authorized leave," said Moreno.

According to bond officers, O'Connor showed up at Eva Irene's home at about the same time he was scheduled to be at work.

"It's a very unfortunate situation, but we took all the legal ramifications that could have happened to protect this woman as much as possible. Unfortunately, it didn't," said Keith Charlton of the Bexar County Criminal Justice Planning and Coordination Department.

Officials said that's because even with the field monitoring unit placed in O'Connor's house, there was no way of knowing exactly where he was going.

The only way bond officers would have been alerted to O'Connor's destination change would have been with a page if he had left the house at a time he wasn't supposed to.

Officials said it would take a device like a GPS tracker to know exactly where a defendant is headed when he leaves the house.

Officials told KSAT 12 News that in some high-profile cases the defendant being monitored would not be allowed to leave the house. But since O'Connor was awaiting trial for only a misdemeanor violation of a protective order, he could leave.