Food, water and air conditioning at a hotel in Egypt where a Lancashire couple died are being probed as authorities try to establish the cause of death.
John and Susan Cooper died while staying at the Steigenberger Aqua Magic Hotel in the Red Sea resort of Hurghada.
The couple's family will "hopefully" find out the results of the tests in 10 days, the chief executive of Thomas Cook said as he promised to do everything to "get to the bottom of it".
It comes after Kelly Ormerod, the couple's daughter, said there was "something suspicious" behind the deaths.
Peter Fankhauser told Sky News: "We have no real evidence what caused the deaths, but what I can promise is at Thomas Cook we are doing everything to support the family and to support the Egyptian authorities... to get to the bottom of it and to get to the cause.
"There is no evidence that it is a carbon monoxide poisoning. We have no evidence but I don't want to rule out anything before I really know the cause."
Mr Fankhauser continued: "Twenty-four hours after the couple died, we had our specialists... in the hotel. They took probes of the food, of the hygienic systems, of water, as well as the air conditioning systems, and all those probes are now in Egypt.
"They are now examining and testing the probes and we support them in doing that, but that takes about 10 days."
Mr Cooper, 69, from Burnley, died in his room while Mrs Cooper, 63, a Thomas Cook employee, died after being taken to hospital, according to Mrs Ormerod.
Their daughter said they were "fit and healthy" before their holiday and in "perfect health" just hours before being taken ill.
A technical team's inspection of the Coopers' room showed there were no toxic or harmful gas emissions or leaks, according to a statement by prosecutor Nabil Sadeq on Saturday.
It also said his office was waiting for a forensic analysis of samples taken from the bodies.
Mr Fankhauser said Thomas Cook decided to move 300 guests out of the hotel 24 hours later as a precaution after becoming aware of an "increased number" of illnesses.
He confirmed that 13 customers had food poisoning but were not in a serious condition.