A Polish tourist who died in an Egyptian resort last month may have been a victim of human trafficking and organised crime, officials in Poland say.
The Polish tourist, named in media reports as Magdalena Zuk, travelled alone to the Red Sea resort of Marsa Alam at the end of April.
Days later, she plunged to her death from a hospital window.
Egyptian security sources and medical staff said the 27-year-old woman took her own life.
There has been speculation the woman was the victim of a sexual assault by hotel staff, but Egyptian security sources have denied that she was drugged and raped.
However, Polish investigators said they are following several lines of inquiry, including forced prostitution, human trafficking and people smuggling.
Local media report that the young woman arrived in the resort, some 750km south of Cairo, on 25 April, and was planning to spend a week there.
But for reasons unknown her plans changed, and she tried to fly home from the local airport, but was not allowed on the plane because she was acting strangely.
She was taken to hospital, from where CCTV footage has emerged apparently showing her acting erratically and being restrained by two men.
Hospital manager Mohamed Sami Gomaa told the privately-run CBC channel she tried to throw herself from a window several times.
Staff said she was later tied to a bed, but managed to escape, attack a nurse and jump from the building.
Mr Gomaa also said no rape check had been carried out because she had not made a complaint.
The Polish foreign ministry has said it is the responsibility of the Egyptian authorities to clarify the circumstances of the death.