Beheading images sent to Labour supporters in Barrow
Letters containing images of beheadings have been sent to 23 people in a Cumbrian town.
Fourteen were sent to Labour supporters in the Barrow area before the general election. Another nine people have now come forward to say they received one.
Police are investigating and say it is "yet to be established if they were all sent at the same time".
Earlier this month Labour councillor Anita Husband described the letter she received as "disgraceful".
"It's like a little booklet which goes on about the Koran and it has got graphic photographs in, not very nice at all," she said.
"It's a bit of propaganda and it's a nasty propaganda," Ms Husband said.
"It is basically to frighten people."
'Very serious matter'
Some of the typed letters with booklets of pictures of graphic violence were sent to people who had displayed Labour election posters in their windows.
Senior lecturer in forensic linguistics at Aston University, Prof Tim Grant, said it was a "very serious matter".
"You can't underestimate the effect this can have on some individuals," he said.
Cumbria Police said the letters, "which appear to be malicious", have been delivered to a number of houses since the end of May.
The force wants to hear from anyone who has been sent such a letter but has not yet reported it.