As police try to get to the bottom of the murder and mutilation of a 17-year-old Pretoria schoolgirl, they have asked anyone with information that can help them solve the crime to come forward.

Anika Smit was raped and killed on Wednesday. Her throat was slit and her hands hacked off.

Police are investigating several possibilities, including that Smit's attacker or attackers cut off her hands to prevent her from obtaining DNA evidence.

They believe she may have scratched the perpetrator, which would have left skin tissue under her finger nails.

They also believe she knew the man as the dogs were closed off in the back yard and there was no sign of forced entry.

The killer took the severed hands with him.

Investigators have asked anyone with information which could help them solve the case to contact Crime Stop.

Anonymous tip-offs can be sent to Crime Line via sms on 32211.