Patsy Stokes Burton, 69, killed in pedestrian accident on Main Street in Upper Marlboro on July 31.

Patsy Stokes Burton was a dedicated bookkeeper who would do almost anything to ensure that the small businesses she worked for were happy. Outside of work, she focused on family and church.

As Burton, 69, was crossing a street in Upper Marlboro earlier this week to take care of paperwork for one of those clients, she was fatally struck by a Prince George’s County bus.

“One of my first thoughts when I heard about the news was, ‘Her clients will be devastated,’ ” Michael Burton said of his aunt. With her, “they didn’t have to worry about whether or not things were going to be done right.”

Burton was crossing Main Street near Water Street about 10:30 a.m. Thursday when she was hit, authorities said. When police arrived, they found her under the bus and pronounced her dead.

“Her back was to the vehicle, and the driver did not see her,” Michael Burton said. “She didn’t know the bus was on her until it was on her.” She was in a crosswalk.

Investigators are working with state prosecutors to review the case before determining whether to file charges, said Lt. William Alexander, a spokesman for Prince George’s police.

County transportation officials are cooperating with the police investigation, said Carol Terry, a spokeswoman for the county’s Department of Public Works and Transportation. Veolia Transportation, the company that has provided transit services for the county for 15 years, will also be involved, Terry added.

“Once we receive their report, the department, along with Veolia, will be doing a thorough internal investigation,” Terry said. “This was a tragic accident, and our thoughts are with the family and the victim.”

Ruth Otte, a spokeswoman for Veolia, said the company would not identify the driver involved in the incident but described her as “fully qualified” and an “appropriately trained driver in good standing with our organization.”

“We are fully complying with the investigation that the Prince George’s County police department is conducting of the accident,” Otte said. She did not say whether the driver has been put on leave.

Burton owned her own company doing accounting work for small businesses, Michael Burton said. He said his family is devastated and “grasping for answers.”

He said his aunt was “kind all the time,” fondly remembering how she taught him and some other children in the family to make Snickerdoodles cookies.

“We rolled them in salt instead of sugar, but she claimed they were the best cookies she ever had,” Burton said. “She was delightful both inside and out.”