The victims include a 23-year-old highway construction worker in Washington state, a 13-year-old Michigan boy riding in his older sister’s car and a Minnesota school bus driver picking up the morning newspaper in front of his home.

All were killed in recent years by distracted drivers who had been texting or otherwise looking at their phones. Yet none of the drivers responsible for those deaths has been ordered to spend more than a few days in jail.

Although there are no national statistics on the results of prosecutions brought against distracted drivers who kill or severely injure people, light punishment appears to be the norm. A review of prosecutions of distracted drivers — cases gleaned from news reports over the past five years that together involved more than 100 deaths — found that few were jailed for more than two months or fined more than $1,000.

Safety advocates and researchers say tougher penalties alone aren’t likely to get drivers to put down their phones. But as with drunken driving a generation ago, they say, stiffer penalties could reduce the reckless behavior if the tougher punishment is combined with education programs, peer pressure and technology to disable motorists’ wireless devices while they are driving.

Nearly one-third of drivers 18 to 64 read or send texts or e-mails while at the wheel, according to the U.S. Centers for Disease Control and Prevention. Distracted driving causes nearly 3,500 deaths and 400,000 injuries a year, the National Highway Traffic Safety Administration (NHTSA) says.

In 2015, the agency estimated that nearly 500 deaths involved the use of cellphones, but experts believe the real number is much higher since the federal database relies on often incomplete information in police reports.

“This is so prevalent and so very dangerous,” said Amy Freedheim, a prosecutor in King County, Wash. “We’ve got to address it. We can’t afford not to. All it takes is just a moment of drift and you’ve altered your life, and you’ve ended somebody else’s life.”

The NHTSA last May published a guide outlining the best methods to win convictions. It was prepared by a team of eight prosecutors, including Freedheim, with police officers and traffic safety specialists from across the nation.

“Sending or reading a text message can take the driver’s eyes off the road for an average of 4.6 seconds,” the publication says. “At 55 miles per hour, the vehicle will travel the length of a football field without any visual guidance.”

The NHTSA guide encourages police to consider using special evidence bags for cellphones to preserve their data and reduce the chance that the information would be lost because of outside interference or static electricity.

It also advises police to demand electronic records from wireless providers, who typically won’t release them without subpoenas, and get statements from witnesses and the suspect driver. “The early interview may reduce the opportunity to fabricate or conspire with others,” the manual says.

Yet no matter how thorough the investigation, experts say, distracted driving is far more difficult to prosecute than drunken driving. Only in the rare case of an eyewitness report or admission by a motorist will police know that a phone was involved.

Perhaps the stiffest sentence in recent years for distracted driving was given to Frank Rychtik. The Wisconsin dump truck driver pleaded no contest to killing motorist Jason Songer, 29, of La Crescent, Minn., and seriously injuring two others in 2014. Rychtik is serving 16 years.

He had been drinking the previous evening and his blood alcohol level remained above 0.04 when he slammed into several vehicles that had stopped ahead of him on Interstate 90 near La Crosse, Wis. At the time, he acknowledged, he was looking down at a Facebook post and did not notice the stoppage.

“Life can change in that second it takes you to look at your phone,” he said in a television interview last year.