More than 60 officers are dedicated to investigating the murder of Malakai McKenzie as it approaches a week since the 19-year-old was killed.
Detectives are continuing to follow-up several lines of enquiry and have searched four addresses with a number of vehicles being seized.
Forensic examinations are also being fast-tracked to ensure vital evidence is analysed and collated as soon as possible.
Senior Investigating Officer, Detective Chief Inspector Tony Heydon, said: “The message from Malakai’s family is clear - they want justice for their son and we are determined that this will happen.
“A substantial amount of investigative work has been carried out over the past seven days with officers from across the East Midlands dedicated to finding those responsible for Malakai’s murder.
“A number of addresses have been searched, several vehicles seized and forensic examinations are being fast-tracked.
“We are confident that more than one person was involved in the incident and believe the offenders may have gathered in and around the area, getting in and out of vehicles 10 or 15 minutes before driving to The Hubb.
“We still need the public to come forward with information, no matter how insignificant you think it could be, as it may prove vital to the inquiry.
“We also still want to hear from people who have information about the vehicles the suspects may have got into after leaving the car park.
“I am incredibly grateful for the support from the community, and our partners, and thank those who have already contacted police with information.”
Mr McKenzie was taken to the Queen’s Medical Centre with serious injuries during the early hours of Saturday 21 April 2012. He died later that day.
A Home Office post-mortem examination concluded that the 19-year-old, from Nottingham, died from a gunshot wound.
Officers believe Mr McKenzie sustained the fatal injury during the firearms incident which happened in the car park of The Hubb, in Hucknall Road, Sherwood, at about 3.30am on Saturday 21 April.
DCI Heydon added: “Please think back to that day. Were you driving through the area at the time of the incident? Did you attend the party at The Hubb? Did you see a group of men gathering in the area prior to the incident or driving away from the venue at speed?
“If you have any information please contact police immediately.”
Two men, aged 19 and 17, were arrested in connection with the incident. They have both been bailed pending further enquiries.
Witnesses or anyone with information is asked to call the incident room on 0115 8446913, or Crimestoppers anonymously on 0800 555 111.