Twin brothers have been arrested over six rapes because police do not know which one is the suspect.
The 25-year-old siblings share near identical DNA and police say it could take weeks to identify which one was at the scene of the crimes.
Six women were assaulted in the hallway of a block of flats in Marseille, France.
The victims have identified photographs of the twins but not which one attacked them.
One of the men was also caught on CCTV camera.
But again both police and the victims can not tell which brother it is.
The brothers, who are unemployed delivery drivers named as Elwin and Yohan, deny the offences committed between September and December last year.
Police chief Emmanual Kiehl said: “It is a highly unusual affair. This pair have almost identical genetic codes.
“It is possible to tell them apart but it could take weeks and we do not have the facilities here in Marseille.
“There are very slight differences in their DNA formed as they were developing in the womb.
“It could take thousands of separate tests before we know which one of them may be guilty.
“Meanwhile, both are being held in custody on a special warrant due to the rare nature of the situation.”