More than 60 officers are now involved in a major police investigation into the fatal flat fire in Douglas at the weekend.
A man in his early 60s, yet to be named, died in the blaze which virtually destroyed a property in Demesne Road.
Forensic officers are carrying out a fingertip search of the area, in what's described as a 'murder style' investigation.
A section of Demesne Road remains cordoned off and could stay closed until the weekend.
Yesterday, police revealed a series of fires were started at nearby properties before the fatal blaze, and those properties remain under police guard.
Chief constable Mike Langdon says the circumstances look highly suspicious and he is appealing for the public to help:
"First of all, if it is the case that we have someone that's setting fire to premises in this way then that individual themselves must be, in my view, significantly disturbed or at least have some behavioural issues that some people may well have noticed.
"I'd be asking anybody that's got knowledge of anybody like that, or has got suspicions of that, that they share them with us.
"The second thing is that we're appealing for anybody in the area of Bucks Road on Saturday, between one o'clock and three o'clock, and specifically around the area of number 59, to come forward.
"And also we want anybody who was in the Peveril Street, Peveril Terrace, Demesne Road area, between midnight and 4am on Sunday, also to come forward please."
If you can help you are asked to ring the incident room on 631263, or the anonymous Crimestoppers line, on 0800 555 111.
Tuesday 24th, March 2009 08:11pm.