Prince George's County police detectives canvassed the neighborhood where Tyson Jerome Barnette was shot with this photo, hoping to turn up leads on how the postal worker was killed over the weekend. (Courtesy of Prince George's County Police)

Tyson Barnette would arrive at the post office in Landover Hills each workday about 10 a.m. He’d change out of his designer tennis shoes, pick up his deliveries and start filling mailboxes in the Prince George’s County community of Kentland. Often it would be after 7 p.m. before Barnette would return to the office.

On Saturday, he was working a new route, one that also would keep him out until after dark, when he was fatally shot.

As Prince George’s police and U.S. Postal Service investigators search for motives and suspects in the case, Barnette’s shooting has spotlighted a change in delivery across the country: The mail arrives later, often at night.

“It’s a hard and dangerous job that we do every day,” said Karen Nance, a colleague of Barnette’s who has been a Postal Service employee for 19 years.

Del. Eleanor Holmes Norton (D-D.C.), who serves on a panel that oversees the Postal Service, sent a letter to Postmaster General Patrick R. Donahoe on Tuesday seeking answers as to why mail delivery after dark has become commonplace.

“Late delivery is now systemic,” Norton said in an interview. “But I did not consider that this posed a risk to life and limb. Now someone has been killed, and we have every reason to look at why mail is delivered after dark.”

Working in the dark poses other hazards besides violence, postal workers say. Carriers can’t see potholes under leaves, angry dogs come out of bushes and homeowners not expecting late deliveries threaten to shoot carriers leaving parcels on porches. At least one female carrier on Tuesday called Nance complaining of someone following her on her route. That carrier returned to the office with undelivered mail.

Postal carriers in Maryland and the District have complained about working in the dark for at least four years, when routes started to get longer and a shortage of staff began, said Ken Lerch, president of the National Association of Letter Carriers branch that covers Montgomery County. Long­er routes, smaller staff and late starts mean it is common for carriers to be delivering mail at 7 p.m. or beyond.

“It’s going to happen again, no question,” Lerch said of harm coming to postal workers.

Donahoe acknowledged in an interview that mail carriers “are working later and they’re on the street longer.”

A smaller workforce is part of the reason, as fewer carriers who retire or quit are replaced by full-time hires. “We have a lot of carriers who have delivered in the dark for years,” Donahoe said. “We like to have them back by 5 o’clock or so, but it’s the changing nature of the business.”

As a substitute carrier, Barnette had been covering Route 3 in Landover for nearly two years while a colleague was on management leave. But Saturday, that co-worker returned, forcing Barnette to sub a different route.

Frank Schissler, who is probing the case for the Postal Inspection Service, said Barnette was a city carrier assistant, a part-time postal employee hired to relieve regular mail carriers of excess work on their routes.

Carrier assistants such as Barnette are necessary, Nance said, because some routes are so long that a single worker can’t deliver all the mail in a single eight- or 10-hour shift.

Even Barnette, who Nance described as a “hard worker,” needed at least an hour of help on the shift he was regularly covering for the past two years.

Nance and other postal employees hope his death will bring about safer work conditions for letter carriers.

“A lot of carriers are still distraught, they’re upset and they’re mad,” Nance said.

Barnette’s grandmother, Willie Ruth Barnette, said she was in a “daze or dream” thinking about the death of her grandson, whom family members called T.J.

“He didn’t talk very much,” Willie Ruth Barnette said. “He was more of a listener than anything. He just had a beautiful smile all the time.”