Baltimore police returned 34 patrol cars to service Tuesday after investigators determined they are not connected to a rape investigation possibly involving a police officer.

That leaves 81 cars still off the streets as investigators continue trying to narrow down the number of vehicles they need to process for evidence in the case, police spokesman Matt Jablow said Tuesday.

Investigators hope to finish the work by the end of the week.

The investigation began Sunday after a woman reported she had been raped after she had been inside a patrol vehicle.

According to an internal memo distributed Monday to some Baltimore police officers and obtained by The Baltimore Sun, the victim reported that she was near the Charles Village Pub when she met a man named “Rick,” who appeared to be a police officer.

The victim reported the man then took her to a residential area near Camden Yards — she didn’t have an exact location — and forced her to have sex, before dropping her back in the Charles Village area, the memo said.

The woman later went to an area hospital to report the incident, the memo said.

With so many cars out of circulation the department has assigned two officers to each patrol car on duty while investigators try to identify cars matching the description given by the victim. Jablow declined to release that description.

“We’ve had to double up some officers in cars, but I would say that so far, it has had minimal impact on our operations,” Jablow said.

He said investigators have been able to talk to the victim but declined to say whether any officers have been interviewed. Jablow would not say whether investigators are able to use GPS systems to track the police vehicles.

No officers have been placed on leave as of Tuesday, he said. The “comprehensive investigation” is being conducted by the department’s special investigation section, along with the Baltimore state’s attorney’s office, he said.