A Swedish thief has proved something of a good Samaritan after they backed up the data on a stolen laptop and returned it to the owner.

A professor at Umeå University in northern Sweden left his bag, containing a laptop, wallet, credit cards and scheduler, outside his apartment door while he went downstairs to collect his laundry. When he returned the bag had been stolen.

He called the police to report the theft, as well as contacting his bank to cancel all the credit cards. Then when he left his apartment shortly afterwards he found the bag had been replaced with almost all the contents still there.

There was a further surprise a week later, when the professor, who wishes to remain anonymous, found an envelope by his door, containing a USB stick onto which the thief had copied all the documents and personal information from the stolen laptop - a process that would have taken hours.

"I am very happy," the unnamed professor told the local Västerbottens-Kuriren newspaper.

"This story makes me feel hope for humanity."

The only thing still missing, besides the laptop, is the professor's library card.