Leonard Stock kept seeing innocent bystanders injured by the vehicle pursuits he’d watch on police reality shows.
“I remember cringing,” he said.
One night, Stock recalled, “I went to sleep and woke up in the middle of the night with this idea of some type of strap going over a tire.”
That was some 20 years ago.
Years of tinkering by Stock — a roofer by trade — would pay off. He did a lot of welding and testing and trial and error, going out into the Arizona desert and practicing on a car driven by his wife; he played the cop, she played the suspect.
In 2018 the Phoenix Police Department became the first to deploy what Stock named the Grappler. And in 2025, the Riverside County Sheriff’s Department became the first law enforcement agency in California to deploy the Grappler’s net, Stock said.
By this July, 16 patrol cars will be outfitted, said Lt. Jason Santistevan, who oversees the sheriff’s program. The devices are assigned to K-9 vehicles, whose officers are among the most highly trained in the department as they are attached to the SWAT team.
“It’s a game-changer,” Santistevan said. “Being in law enforcement for about 22 years, this is probably the best technology we have right now at stopping pursuits … preventing them, as well.”
Here’s how the Grappler works:
A special bumper loaded with a high-strength nylon and polyester net is attached to the front of the police car. After getting within a few feet of the suspect’s vehicle, the officer presses a button that lowers the arms holding the net.
The leading edge of the net is five feet from the police car. When the net touches a rotating tire, it wraps around the single tire. The police car, tethered to the suspect’s car by a 30-foot-long cord, then slows to bring the pursuit to a gradual halt.
Each device costs $5,270, not including installation and training. They are not for sale to the general public.
“Not at any price,” Stock noted.
The net can be used once; then an agency sends them to Stock for a credit.
Some officers, Stock said, say the Grappler looks like something that might be found on the Batmobile.
“I talk to police officers constantly,” said Stock, 59. “Almost every time, someone comes up to me and tells me they thought it was just a gimmick.”
(Courtesy of Riverside County Sheriff’s Department)
But now, he said, Stock Enterprises and the 22 employees in its Phoenix office support 165 agencies in 35 states that use the Grappler.
Among them is the Washington County Sheriff’s Office, which Sgt. Lucas Alfred said was the first to deploy the Grappler in Utah. The department has 12 patrol cars equipped with the device and plans to outfit all 22, he said.
“With the Grappler system, we are doing this at speed and we are able to immobilize these cars in a safe and predictable way.”
So far, that agency hasn’t had to deploy the Grappler on a suspect.
The San Joaquin County Sheriff’s Office in Northern California has since deployed the device, and a third agency in the state has as well — Stock won’t reveal that department, thinking it might prefer to keep the bad guys in the dark.
Video: Watch a Riverside County sheriff’s Grappler demonstration
Unpredictability has long been the bane of pursuits.
The lieutenant said that if a deputy is concerned about being tethered to a suspect’s vehicle only 30 feet away — such as if he believes the suspect has a gun — he can press an emergency-release switch.
The safety gained from ending the pursuit with the Grappler instead of with a PIT maneuver, when an officer purposely nudges a suspect’s car to spin it, or a spike strip — both strategies can expose deputies to danger — outweighs the danger of being tethered to the car, Santistevan said.
“It’s kind of frustrating,” Santistevan said, “because we can use spike strips, and now we’re just chasing a guy with flat tires. It doesn’t stop it.
“The thing about PIT maneuvers, you cannot always control the actions of the car,” the sheriff’s lieutenant said. “And let’s say, for example, it’s a suspect driving a stolen vehicle. We PIT the vehicle to stop the pursuit. Now we have damaged a victim’s car, and that was one thing we were trying to avoid.”
The Grappler, Santistevan said, can address a host of dangers.
It used to be that police mostly chased stolen cars, he said.
“These pursuits now, a majority of the time, it’s not just vehicle theft,” Santistevan said. “These guys are armed with guns. They’re about to commit a different crime, and they’re using a stolen vehicle. And so, with that being in mind, today’s pursuits are a lot more dangerous now.”
That’s why the Riverside County Sheriff’s Department’s goal is to use the Grappler to stop pursuits before they start.
Already in 2026, besides other “grapples,” the Sheriff’s Department has done five preemptive ones on homicide suspects. Instead of turning on the emergency lights and siren — which Santistevan said would guarantee that the suspect would flee — the officer deployed the Grappler as the suspect began to drive away.
The targeted car must be going at least 5 mph to use the Grappler, and the department has made several 100-mph grapples.
A couple of weeks ago, Santistevan said, a suspect attempted to enter a freeway in the wrong direction.
“If you think of that scenario,” the lieutenant said, “and you think about all these preemptive grapples that we’re doing now, preventing pursuits, one of the things that we can’t put a value on … what did we just prevent?
“If we didn’t have a Grappler system, that car went on the freeway, we could add a fatality.”
The untraditional end to the pursuit can leave the suspect confused and less likely to resist arrest, too, Santistevan added.
“We are in control of him,” Santistevan said. “It gets in the suspect’s head — surprise. What just happened? He doesn’t have time to think of the other things.”
Despite the Grappler’s success, Stock said he’s not one to pat himself on the back.
“I try not to think about how I am the one who came up with something that actually stops the vehicle,” said Stock, who has given up roofing jobs for now. “What I think most about is the stress in running a company.
“There was almost no stress in roofing, compared to now,” he said. “It was rewarding, giving people a new roof, but I think this is off-the-charts rewarding, just giving police officers another tool.”