Handing her hearing-impaired husband some documents, she asked him to "watch my stuff" while she took pictures across the street of places where her ancestors were raised. Thinking she meant only the records in his hand, he took those and got in the car.
By the time Schneider returned 10 minutes later, the briefcase was gone. She assumed her husband had put it in the trunk, and the pair left for dinner.
They only discovered the records were missing when they returned to the library later that evening to continue their research.
"My poor husband was so upset," Schneider said. "He felt like it was his fault."
A panicked search from Washington Street to Antietam Street failed to locate the briefcase.
"We went through dumpsters, we went everywhere. I can't tell you how upset I am," said Schneider.
While she has always been interested in her family's history, Schneider only began her serious research several years ago to give her father a hobby after he had heart surgery.
"It's given him a whole new lease on doing things," she said.
Over the past few years, her entire family has taken an interest in her growing collection. Her father and each of her seven siblings has called since the briefcase was lost.
"It's been such a tie with my father, and it's really brought together my whole family," Schneider said.
Schneider said the research of her family in Washington County revealed several interesting stories. She learned her mother was distantly related to a man named John Anderson, who served as the town crier, a constable and the unofficial Hagerstown historian during the 1800s.
She learned about Anderson through a lengthy obituary that was published about him.
In addition to her four visits to Hagerstown, Schneider has visited New York, New Jersey, Pennsylvania and Maryland to collect the information, and called as far away as Ireland.
"It's probably cost me thousands of dollars to put it all together, with all the trips and copying and everything," she said. "And it's not worth a thing to anyone else."
Although she rarely took the originals with her, Schneider was too busy at work during the week prior to the trip to copy them. The briefcase contained about two-thirds of her research and a number of one-of-a-kind documents.
She also said she stumbled across some of the records by sheer luck and may never be able to locate them again.
"I just feel like somebody died," she said.
Hagerstown Police took a report on the incident, but have not learned anything more about the case, said Sgt. Ronald Graves.
Anyone who locates the briefcase can contact the Hagerstown Police, drop it off at the Washington County Free Library or call Schneider at 1-914-735-5198.