The MP for Northavon, Steve Webb, has written to the Home Secretary demanding an urgent review of open prisons, after the murder of Karolina Mikolajewska.
Mr Webb says lessons need to be learned from the case
Police believe Clive Hayes, 54, killed the 20-year-old Polish careworker whose body was found in his flat near Bristol last month.
It was revealed that Hayes was a serial rapist who was released from Leyhill Open Prison in 1999.
Mr Webb said lessons needed to be learned from the case.
"If it is indeed the case that he is the person who perpetrated this dreadful murder, then that's where the questions have to start, " he said.
Serial rapist Hayes was released from Leyhill Open Prison in 1999
"So what I've done is tabled a written question to the Home Secretary, to ask him to look in great detail at what really has gone on, because at the very least we have to learn lessons from it.
"One of the problems is that with a huge prison population there's pressure basically to use every available space.
"I think that means that the mix of people at Leyhill is changing, it's different to what it used to be.'"
Police are continuing to investigate whether a body found inside a car which crashed into a shop in Thornbury and burst into flames is that of Hayes.
A spokesman said: "As no dental records are available for Mr Hayes, police are using forensic techniques, which is a far lengthier process. "