Dozens of cats have been reported missing from homes around the town over recent weeks, prompting owners to share their stories over Facebook and compile a body of evidence for the police.
Deni Parkes, who created the group, said there was an “extraordinary number of missing cats” in the town.
“You expect cats to be run over, as sad as it might be, but you don’t just expect them to disappear,” she said.
“I decided we should set up a page and monitor the whole area to identify where these cats are going missing from so we could take that to the police and find out what’s going on.”
Mrs Parkes, 50, who lives in Hatfield Road with her husband, son and their two pet cats Jasper and Mya, said she was overwhelmed by the response to the group so far.
In just a day, stories of missing cats came flooding in to the group from distraught animal owners desperate to be reunited with their pets.
In some cases, more than one cat has gone missing from the same family, with one owner losing all three of his pets over the course of only a week.
“Quite a lot of cat owners are getting quite jittery about letting them out of the house because they are so scared about what might happen,” Mrs Parkes added.
“It’s just a tragedy because some of them have been missing for several months and there’s no sign of them – either someone has killed them or taken them in.”
Others commenting on the group’s page have expressed similar concerns.
“I think there’s something very strange going on, I know cats will wander off but the sheer number of missing cats is alarming and upsetting,” said one member.
To join the group, search for “Ipswich missing cats” on Facebook.
A Suffolk police spokesman declined to comment.