Detectives investigating a double fatal fire in Northern Ireland are still trying to determine why someone started the blaze.
Police checkpoints have been mounted in Dungannon, Co Tyrone, where Betty McGirr (71) and her daughter Deirdre McGirr (38) died last Saturday night.
Betty McGirr was visiting her daughter when the inferno started at the back of the house in Dunlea Vale at about 10pm and ripped through their top-floor flat.
A third person, a Portuguese man understood to be Deirdre's partner, escaped unhurt and is not suspected of involvement with the fire.
Investigators returned to the scene of the blaze last night in a bid to gather more information about what happened.
Detective Chief Inspector Richard Harkness, officer in charge, said: "We are working to piece together the events of last Saturday night and, at this stage, we are keeping an open mind as to the exact circumstances.
"We believe the fire was started deliberately but we are still working to determine exactly what happened."
The senior PSNI officer launched a fresh appeal for information.
"We need to hear from anyone who noticed any kind of activity around the flats on Saturday evening, whether this was people gathered in the area, people calling to the flats or vehicles around the area," he continued.
"We also want to talk to anyone who spoke to either Betty or Deirdre last Saturday, April 14.
"In addition, we would like to talk to anyone in Dunlea Vale and Dunavon areas who has had their wheelie bins interfered with or set on fire in the past two years.
"That is why we will be back at the scene on Saturday evening, mounting vehicle checkpoints and talking to local people to make sure we collect every possible piece of information in this case.
"I would ask anyone in the area who knows anything about what happened to come and talk to us."
PA