An Atchison, Kan., woman pleaded guilty Friday to hindering prosecution for her role in a man’s attempt to cover up a vicious convenience store robbery.

Letah Gerdes, 40, could serve up to four years in prison for what she thought was a harmless beer run last June.

Sean Cave, also of Atchison, had earlier gone to a convenience store in Winthrop, Mo., where he robbed the clerk and slashed her throat. He later asked Ms. Gerdes for a ride to the store to buy some beer, she testified Friday.

Mr. Cave earlier admitted to going back to the store to steal surveillance equipment, and upon discovering the clerk still alive, he again tried to kill her. Mr. Cave was sentenced to life plus 50 years in prison.

The clerk, Kim Dejonge, 19, has been described as a miraculous survivor. In spite of her injuries and blood loss, she crawled out of a beer cooler and was able to be transported by emergency workers.

Ms. Gerdes had earlier been charged with robbery, but her testimony of her role didn’t match with the crime, and Buchanan County Circuit Judge Pat Robb rejected her plea. After two meetings between the judge and attorneys, Assistant Buchanan County Prosecutor Ron Holliday on Friday amended the charge to hindering prosecution.

“We simply had no evidence to believe that she knew about it prior to driving him there,” Mr. Holliday said Friday. “(For robbery) she would’ve had to know or assist during the crime.”

Mr. Holliday stuck with his recommendation of 120 days in a prison institutional drug and rehabilitation program, followed by the possibility of probation. Mr. Robb warned Ms. Gerdes that he may reject that agreement when he sentences her May 27.

Mr. Holliday noted that Ms. Gerdes was cooperative with authorities when she was apprehended after driving back through Winthrop after she dropped Mr. Cave off at a house in Atchison.

“She did provide information that aided in the almost immediate arrest of Mr. Cave, but I also felt she deserved punishment — stiff punishment,” Mr. Holliday said.

Mr. Robb took pains Friday to be sure Ms. Gerdes had technically committed a crime. He focused on Ms. Gerdes driving away from the store, despite knowing that Mr. Cave had stolen a computer tower and later implying that he’d hurt or killed someone.

Ms. Gerdes was represented by public defender Michelle Davidson.

Joe Blumberg can be reached

at joeblumberg@npgco.com.