The deaths of five couples in England that were believed to be murder-suicides may actually have been slayings carried out by a serial killer who has been on the loose for nearly a quarter century, a report said.

Stephanie Davies, the senior coroner’s officer for the Cheshire police, produced a nearly 200-page report about the death of two couples in 1996 and 1999 in the wealthy town of Wilmslow, the Sunday Times reported.

The report questions whether their deaths, which were believed to be murder-suicides, were actually killings committed by a suspect who is still at large. The couples reportedly had happy marriages and neither husband had a history of violence toward their wives.

Davies is now investigating if the two cases are linked to three other supposed murder-suicides, all which happened in the north of England in the past 25 years, according to the report.

One of the other apparent slayings is the 2000 deaths of couple Michael and Violet Higgins in Manchester, according to the report.

At the time, police believed Michael beat Violet to death with a rolling pin then strangled himself to death with a coat hanger.

The coroner at the time wrote the apparent murder-suicide was a “very sad end to many years of apparent happy marriage,” the Guardian reported.

They added the “terrible violence took place that was completely out of character with Mr. Higgins,” according to the report.

Davies put together her dossier by filing a number of Freedom of Information Act requests about murder-suicides in the Northern England and finding the three that shared “striking” similarities to the deaths in Wilmslow, the Times reported.

“We are in receipt of the report and it is being reviewed. This is a piece of research which has been undertaken by the staff member, independently from her role within the constabulary,” the Cheshire police told the Guardian in a statement.

“As with any case that has been closed, where new information comes to light it is reviewed and acted upon if appropriate. We have notified both Greater Manchester police and Cumbria constabulary,” they added.