A computer glitch led to the temporary loss of GPS monitoring for released sex offenders and parolees in Wisconsin Tuesday, according to the State Department of Corrections, which led to the detainment of 139 Wisconsin sex offenders.

Signals transmitting the location of about 16,000 people nationally were blocked for about 12 hours, including about 300 people in Wisconsin.

The DOC maintains the program failure could not have been prevented on their part.

“Due to a system failure beyond our control, we faced a challenging and unprecedented event for our Electronic Monitoring Center,” Wisconsin DOC Secretary Rick Raemisch said in a press release Wednesday.

Most of the former inmates being monitored by GPS in Wisconsin are sex offenders, Linda Eggert, spokesperson for the Wisconsin DOC, said.

According to Eggert, 139 sex offenders and parolees were detained on Tuesday by local police and probation officers.

“They were released when it became clear regular monitoring had resumed,” Eggert said.

According to Eggert, the offenders were not aware they were no longer being monitored during the program failure.

Although the DOC was unable to pinpoint real-time locations during the system failure, the supervised offenders’ movements were still recorded and were available for review when the system began running again Tuesday night, according to the DOC.

The offenders were kept in local jails until their recorded movements Tuesday could be reviewed for possible violations, the DOC said.

The company responsible for the glitch was BI Inc., a national monitoring company that stores data and provides GPS tracking on released inmates in 49 states.

BI Inc. said in a statement their system shut down after reaching its capacity for stored data Tuesday morning.

BI Inc. said the system reached its capacity of about 2.1 billion records, which resulted in an unexpected system shutdown.

The company said they began contacting state correctional departments within five minutes of the problem being identified, and any alerts on offender movements were reported when the server began operating again Tuesday evening.

Monica Hook, a spokesperson for BI Inc., said in a statement the company has fixed the program glitch.

“We believe the issue is resolved as we have expanded the database threshold to more than 1 trillion records,” Hook said. “In the meantime, we are working with Microsoft to develop a warning system on database thresholds so we can anticipate these issues in the future.”

BI Inc. database expert Len Silverston blamed the problem on a programming error, not a memory shortage and said it would have been difficult to prevent.

Wisconsin uses BI Inc. as a way to collect and store data on GPS tracking locations, addresses, names, breathalyzer results and electronic monitoring records aimed at keeping offenders at home or away from locations declared off-limits by the courts, according to BI Inc. spokesperson Jock Waldo.

Eggert said Wisconsin has not always used GPS monitoring to keep track of offenders.

Prior to the use of GPS, monitoring the whereabouts of sex offenders and other freed felons was largely left to probation officers, Eggert said.