Police have made an appeal for information after a 29-year-old man fell from the ninth floor of a block of flats.
Shumin Hussain fell from the flat in Telford Court, St Albans, Hertfordshire, just after 2200 BST on Sunday.
He died a short while later from multiple injuries.
Detectives believe the key to Mr Shumin's death lies with the people who were in the flat shortly before he died.
A Hertfordshire Police spokesman said Mr Shumin, who lived in Doggetts Way, St Albans, was at the flat on Sunday evening, but they are keen to trace anyone else who was there.
A 40-year-old man and a 25-year-old man both from St Albans have been arrested on suspicion of murder and are currently in custody helping police with their enquiries.
A 26-year-old man, a 30-year-old woman and a 25-year-old man have been bailed pending further enquiries and a 26-year-old woman has been released without charge.
Detective Chief Inspector Colin Sparrow said "Although we have arrested a number of people of people we still need to trace anyone else who was at the flat so that we can establish exactly what happened and how Shumin came to his
"We know that there are people who haven't made themselves known to police who were in the flat on Sunday night.
"These people may have vital information and we would urge them to come forward and tell us what they know."