After Nhazel Warren was charged this summer with carrying a gun in public, a judge freed the 19-year-old on the condition that the Los Angeles County Probation Department track his movements with a GPS device.

When Warren was arrested three weeks later on suspicion of robbing an elderly couple, a different judge let him out again with another provision for GPS tracking.

But even as the court doubled down on Warren’s ankle monitor, prosecutors allege he robbed two more people in September and October.

In an attempt to track his whereabouts, Los Angeles Police Department detectives served a search warrant on the contractor operating Warren’s GPS monitor. The company could not determine where it was located at the time of the thefts.

Detectives took Warren into custody last week, his fifth arrest in five months, court records show. He pleaded not guilty to charges of evading police, resisting arrest, carrying concealed weapons in public, assault with a firearm and four counts of robbery. His lawyer declined to comment.

Warren’s case raises questions about how effectively the Probation Department supervises pretrial defendants at a time when judges are increasingly turning to GPS tracking as an alternative to jail.

In an emailed statement, probation officials said the department interviews defendants and conducts a risk assessment before equipping them with ankle monitors.

In August, the most recent month for which the Probation Department provided figures, 402 of the 1,438 people under GPS tracking had absconded, according to the statement.

Another 231 defendants let the batteries in their ankle monitors run out, meaning they had also possibly fled, according to the statement. Additionally, 142 defendants failed to appear for appointments with their probation agents.

As the pendulum of public opinion has swung away from requiring cash bail, probation officials have framed the monitoring program as a more equitable way to ensure people show up for court while still keeping to the public safely.

Pretrial release allows people to keep their jobs and care for their families instead of waiting for trial in jail. Probation officials, prosecutors and judges generally consider GPS devices to reduce a defendant’s risk of absconding or committing a new crime.

In Los Angeles County, the Probation Department’s GPS program was designed to allow law enforcement authorities to track defendants in real time and establish a record of their whereabouts. But records filed in Warren’s case show that’s not how the Probation Department and its contractor, Securus, are running the program.

When detectives served a search warrant on Securus, the company did not turn over information from Warren’s GPS monitor, records show. A Securus analyst said the data was so flawed that he would feel “uncomfortable” testifying that it was accurate.

“To that end,” he wrote in a letter to the LAPD, “we are unable to certify any of the data during that time period.”

A Securus spokesperson acknowledged a question from the Times but had no comment. The Probation Department pays Securus about $350,000 a month to operate its GPS system, probation officials said.

Warren had already been arrested twice in two months, on suspicion of leading police on a high-speed chase and illegal weapons possession, when LAPD officers stopped him at 55th Street and Denker Avenue on July 15, they show court records. They searched him and found a gun in his underwear.

According to a motion filed by his attorney, Warren said he carried the gun because he feared his $20,000 Rolex watch would be stolen.

After pleading not guilty to possessing a concealed weapon in public, Warren was released subject to electronic monitoring by the Probation Department, court records show.

That’s when probation officers first attached a GPS device to his ankle.

Detectives arrested Warren again three weeks later on suspicion of robbing an elderly couple at gunpoint. Prosecutors accuse Warren, who was not yet under GPS monitoring at the time, and Daelan Reed, 18, broke into the couple’s Mid-City home on July 2.

The 85-year-old victim, who asked to remain anonymous for fear of retaliation, told The Times that he woke up at 4 a.m. to find two men wearing hoodies, masks and gloves in his room.

They told the couple not to move and that they wouldn’t get hurt.

She watched as her jewelry box was emptied of a diamond engagement ring and necklaces, bracelets and earrings she had received as gifts from her parents and husband.

“He even took the pearls my mother gave me,” she said.

One of the robbers ordered her 80-year-old husband out of bed, pointed a gun at his back and demanded cash, checkbooks, credit cards and the couple’s PIN, she said. The couple took their car keys from a kitchen drawer and drove off in the couple’s BMW.

In the days that followed, the thieves withdrew as much money as they could from the couple’s bank accounts, the woman said.

“What they have taken from me, in addition to the tangible things, is my sense of security,” he said. “My love for my own house. I don’t look at strangers the same way. “It has given me a 180 degree turn.”

After arresting Warren, detectives searched his mother’s home in Long Beach. They found four guns and seized $21,000 from a nightstand and $2,583 from Warren’s pocket, his attorney, Geoffrey Ojo, wrote in court documents. Ojo demanded the return of the $21,000, which he said belonged to Warren’s mother, a “gainfully employed” health care professional who earned $136,859 in 2023.

After pleading not guilty to robbery charges, Warren was released again after posting $150,000 bail. A judge ordered the Probation Department to put Warren through a second GPS tracking program, listing the conditions of his release as “without force, violence or weapons.”

Two weeks later, police say, Warren robbed a man who was returning to his Bentley SUV after shopping at Bristol Farms in Woodland Hills. Police say Warren and another man wearing dark sweatshirts and masks knocked the victim to the ground and stole his watch and phone.

A black BMW with a stolen license plate was waiting nearby, the detective said. Emily Delph wrote in a search warrant affidavit. An hour later, the BMW was seen in the downtown Los Angeles jewelry district, where the suspects were likely trying to sell the stolen watch, Delph wrote.

Detectives found video of the suspects entering a jewelry business. Delph recognized one of them as Warren. He requested a search warrant on Oct. 16 to obtain GPS data from Warren’s two electronic monitoring cases. Historical data would determine whether he was present at the Woodland Hills robbery, Delph wrote; Live tracking information would help LAPD locate and arrest you.

She got neither. In a letter, a Securus analyst said the data was so imprecise that he was unwilling to swear to its accuracy in court.

“We would never put them in the position of including our data as evidence and would not feel uncomfortable testifying to its accuracy,” wrote analyst Jeff Marino.

Marino did not respond to requests for comment. He did not say in his letter why the data was inaccurate or how widespread the problem was.

Some authorities outside of Los Angeles County have questioned the reliability of the contractors responsible for monitoring GPS trackers.

Louisiana prosecutors this year charged a Mississippi-based contractor, AEM, with negligent homicide after a defendant under his supervision shot and killed his wife before committing suicide in 2021. The defendant repeatedly violated an exclusion zone ordered by the court around his wife’s home without provoking a response, prosecutors allege.

On October 23, Warren appeared at the Clara Shortridge Foltz Criminal Justice Center in downtown Los Angeles to be arraigned in the gun possession case for which he was first issued a GPS device. He pleaded not guilty and was allowed to continue electronic monitoring.

Later that day, prosecutors allege, Warren returned to Woodland Hills. A man was talking on the phone when he noticed a black BMW double parked next to him on Ventura Boulevard around 8:30 p.m.

The man, who asked to remain anonymous out of fear for his safety, told the Times that two people got out of the BMW. They wore masks and pointed guns in his face, he said. When he heard them cocking their weapons, he thought they were going to kill him. He shouted, “No, no, no, stop!”

They demanded the Breitling Navitimer on his wrist. He loved the silver watch with the gray strata dial, number 193 of only 1,000 made. “It was the first expensive watch I bought,” he said. “I had been working very, very hard.”

He handed the $10,000 watch to the masked men.

Warren was arrested the next day. He and two other men were charged with both robberies in Woodland Hills. Warren pleaded not guilty Monday in a Van Nuys court.

Police have not recovered the Breitling. Its owner wonders if the thieves would kill someone before locking him up.

“Are we really going to wait until we get to that point to do something?” asked.

A judge set Warren’s bail for the robbery at $150,000.

He posted it and was released, still under court-ordered GPS surveillance.