A 27-year-old man who was found with fatal injuries in an alleyway in Nottingham city centre died from a gunshot wound, tests have revealed.
Bernard Langton, of Bulwell, was found near the Pitcher and Piano pub in the city's Lace Market area early on Monday. He died on the way to hospital.
Police said an "altercation" had earlier broken out in the Paris nightclub, in Broadway.
Officers said the motive was unclear but thought it was not a random attack.
A post-mortem examination carried out on Monday revealed Mr Langton died of a gunshot wound.
Officers said they were continuing in their search for the weapon and forensic experts are examining the scene.
Cordons remained in place in several roads in the Lace Market and Hockley areas, including High Pavement, Weekday Cross, Pilcher Gate and St Mary's Gate.
Police said a second man was also treated for a stab wound which they believe may have happened in or around the area of the nightclub. His injuries are not life threatening.
Ch Insp Paul Cottee from Nottinghamshire Police said: "The circumstances and motive surrounding this murder are still unclear.
"We are continuing to speak to a number of witnesses and know there will have been a lot of revellers in the Lace Market area, who may not yet have spoken to police.
"Their information could be vital to the inquiry and we would urge them to contact us.
"This is the first fatal shooting that we have had in Nottinghamshire since September 2006, and it has shocked the community. We do not believe this to be a random attack."
Alan Simpson MP, who lives in the area, said some of his neighbours had reported hearing gun shots in the early hours of the morning.