MIAMI -

For 15 years, Miami-Dade County has used ankle monitors on accused criminals awaiting trial. Home detention is a way to free up space in county jails and save money.

But after three months of investigations, Local 10 has uncovered dozens of cases of these ankle monitors malfunctioning.

One of the most recent malfunctions happened to suspect Sandor Guillen.

Sandor Guillen

"He killed an innocent girl," said Kirk Camacho, father of Kaely Camacho. "I just want justice to be done."

Despite objections, the courts placed Sandor Guillen (pictured, right) on house arrest and gave him an ankle monitor. He is accused of vehicular homicide and DUI manslaughter in the death of 13-year-old Kaely.

Since then, Guillen's ankle monitor has malfunctioned at least once. Miami-Dade's Correction Department has not yet released the specifics regarding the malfunction, despite a Local 10 request.

"I don't totally trust the anklet," Kirk Camacho said. "It does anger me. It is very annoying and worrying."

Local 10 Investigates

Trenise Adker

Trenise Adker (pictured, left), who is accused of killing her boyfriend, said her ankle monitor malfunctioned last month.

"Sometimes, it kind of acts up," she said. "It's a lot of malfunctions with it."

Records show at least 35 ankle monitors have malfunctioned in Miami-Dade County so far this year. In all of 2012, only 18 ankle monitors malfunctioned.

"Does that worry you?" Local 10's Ross Palombo asked the lieutenant in charge of the program.

"It's something worth looking into," said Miami-Dade Police Corrections Dept. Lt. Pablo Quinones.

Battery levels

Officers use computers to track more than 500 ankle monitors at any one time, allowing them to see each one's location and battery level. When tampered with, the devices send out alerts.

Officers log each alert and each time an alert is checked and cleared.

Quinones said every alert is investigated. But records show that so far this year, for one specific tamper category, there have been 1,005 alerts but only 714 items checked.

"How come the numbers don't match?" asked Palombo.

"I would have to look further at that," said Quinones. Despite those numbers, he maintained that all cases are checked.

Quinones said a recording issue cause the discrepancies between the numbers of alerts and checks. He said it was corrected following Local 10's investigation.

"Should victims be concerned?" asked Palombo.

"You could always be concerned, yes. It's not a perfect world -- it's not a perfect system," replied Quinones.

In one recent case, the Miami-Dade Correction Department took two hours to replace an ankle monitor. Although asked, it has not released any other response times. The company that make the devices, Sentinel Offender Services, would not comment on the recent spike in malfunctions.