WEST VALLEY CITY — Charges have been filed or are being screened against 11 people in connection with the theft of large cellphone batteries across the Wasatch Front since 2017, resulting in $1 million in losses and creating a danger to 911 emergency service.

"These thefts posed a direct threat to the safety of the public. If power goes out, they ensure the public can still call 911 in case of an emergency. Without the batteries in place, people may not be able to reach first responders in a time of need," said West Valley police spokeswoman Roxeanne Vainuku.

On Thursday, West Valley police announced the culmination of a monthslong investigation that also included Unified police and the U.S. Marshals Service.

Beginning in 2017, Comcast alpha-cell batteries began disappearing across the Wasatch Front, including Salt Lake, Davis and Summit counties.

"The heavy industrial batteries provide backup power for cable, broadband and 911 phone service during power outages and are valued at approximately $180 each. The stolen batteries can be sold to metal recyclers for lead and other metals," West Valley police said in a prepared statement.

"The batteries are housed in secured steel utility boxes, but thieves had successfully been able to break into the vaults containing the batteries, cut wires connecting the batteries and then haul the batteries away to be sold for scrap."

The batteries are about 70 pounds each. The first reported theft was July 31 at 4174 S. 2000 East, according to charging documents,

The big break came shortly after that theft when an alert citizen was able to take a picture of a person stealing batteries from a utility box in Holladay. West Valley police detectives were able to find that man, make an arrest, and based on that arrest, "were able to develop extensive information about suspects and suspect vehicles."

In August, investigators placed batteries with GPS tracking devices at various locations across Utah.

"The GPS trackers on the batteries allowed Comcast personnel to identify when a battery was being removed from its power source, as well as provide the ability to follow the battery’s physical location," police said.

As U.S. marshals followed the GPS batteries, it resulted in the recovery of some of the stolen batteries and the discovery of where batteries were being sold as scrap metal, according to court documents.

In November, Mark Hasselblad, 40, was charged in 3rd District Court with engaging in a pattern of unlawful activity and money laundering, theft, and three counts of criminal mischief, all second-degree felonies.

Similar charges were pending against 10 others, Vainuku said.