The Global Positioning System (GPS) has important applications for most everyone, from the military to daily commuters.
GPS technology is used to track thousands of convicted criminals nationwide, including in San Diego County where Sentinel Offender Services monitors more than 250 pretrial defendants, sentenced offenders and parolees.
NBC 7 Investigates uncovered some alarming glitches in the system used to watch some of those offenders in San Diego.
Three years ago, both the San Diego County Sheriff's Department and its probation department contracted with an Irvine-based GPS monitoring company called Sentinel Offender Services.
It monitors a wide range of the county's offenders, from those convicted of sex crimes to drunken drivers.
"It permits someone to have structure around their life. They have rules. They have limits, and they have boundaries," Sentinel Divisional President Darryl Martin said.
The departments rely on Sentinel to keep track of when the equipment fails. But as NBC 7 Investigates learned, the company won't say how often that happens.
Lt. Holly Mitchell oversees the sheriff's department's County Parole and Alternative Custody program (CPAC), which has a contract with Sentinel.
"As long as that device is properly charged and it's working, we know where they are any given time of the day," Mitchell said.
The job of keeping track of criminals is a very serious and precise job, but NBC 7 Investigates found out Sentinel's programs and policies may not be.
"The county of Orange terminated our long standing relationship with Sentinel,” Orange County Supervisor Todd Spitzer said.
Orange County first contracted with Sentinel in 1986. Spitzer lost faith in the vendor after a random 2013 internal audit of 143 cases revealed more than 15 instances of gross negligence, most involving lost contact.
"In some cases, up to a month, Sentinel had no idea where that probationer was," Spitzer said.
He said Sentinel also did not report probation violations and equipment malfunctions, creating a dangerous situation where participants were not checking in and able to use drugs and alcohol.
"We're not proud whenever we make a mistake, and there were some mistakes made in Orange County, and I think that's where I should leave that,” Martin said.
Orange County findings prompted a Los Angeles County audit of Sentinel's services in its probation department.
In a copy obtained by NBC 7 Investigates, some of the discrepancies include 51 of 196 GPS clients having to exchange their equipment during a two-month period in 2013 due to malfunctions. Violent offenders, including sex offenders, went unmonitored for periods of more than five days.
Auditors called it "Unacceptable Service." Despite the findings, LA County kept its contract.
“Were there lessons learned in Orange County? Absolutely there were lessons learned . So we enhanced our training not only for our staff but for our customers," said Martin.
"In Los Angeles County, we definitely made some modifications, some changes to the monitoring equipment with the goal of it performing better," he added.
In San Diego, NBC 7 Investigates found Sentinel's performance has never been audited and the local agencies don't keep track of faulty devices
"If you are asking if we are monitoring to see if 15 of our 20 devices are working ongoing, we are not doing that here," Mitchell said. The sheriff's department is relying on Sentinel to that, according to the lieutenant.
Martin said the company it notifies the proper authorities when contact with a GPS client is lost.
"Do you alert the sheriff's department?” NBC 7 Investigates asked.
"Absolutely,” Martin said. "Every time?” NBC 7 Investigates asked. "Absolutely," Martin said.
The San Diego County Probation Department also uses Sentinel to monitor high-risk sex offenders.
Program monitor Deputy Chief Lorrain Fernandez declined a camera interview. But in an email, probation spokesperson Michele Clock told NBC 7 Investigates, "Probation does not keep records of instances when Sentinel GPS devices malfunctioned. Ongoing maintenance and monitoring of the devices is handled by Sentinel.”
Since Sentinel keeps the maintenance records, NBC 7 Investigates wanted to know how often its system malfunctions when monitoring San Diego offenders.
"It's falling within industry norms; however I am unable to communicate to you the number of failures that occurred in San Diego,” Martin said.
Martin said the industry's normal failure rate is between 5-10 percent, less than what Orange and Los Angeles counties found during their audits.
Without its own audit, San Diego County is taking Sentinel at its word.
Sentinel keeps a record of equipment and operator malfunctions that occur with its San Diego participants, although Martin said that list is not shared with the sheriff's department or probation.
Martin said such discrepancies, however, can be discussed at quarterly client meetings