Gardaí are renewing their appeal for information about the murder of Dean Johnston in Dublin, more than four-and-a-half years ago.

The 21-year-old was shot dead in the Moorefield estate in Clondalkin in May 2011.

Gardaí believe there are still a number of people who were present on the night of the murder who they have yet to identify.

Dean Johnston died after he was shot a number of times as he sat in the back of a friend's car just 100 yards from his own home in Clondalkin on the evening of May 25, 2011.

Detectives say his murder was a targetted attack sparked by a local dispute and was not gang related.

Detective Inspector Richard McDonnell said: "We believe that there are persons out there that have information that could be very beneficial to the case and could help us to secure a conviction.

"Perhaps you were aware of suspicious activity in the run up to or on Wednesday, 25th May 2011. Even the smallest piece of information, which may seem insignificant, might help with the investigation."

"We are particularly interested in speaking to any residents of the Moorefield estate who saw something relevant. Gardaí in Lucan can be contacted on (01) 6667300. If they prefer to give the information anonymously, they can call Crimestoppers on 1800 25 00 25."

Gardaí say they have explored 500 lines of inquiry, taken 400 statements and have more than 300 exhibits relating to the case.

They say there are still a number of people who were in the area on the night who have not come forward yet.

So far nine people have been arrested in relation to the investigation, but nobody has been charged.

Spokesperson for Crimestoppers Cian Connaughton is appealing for anyone with information on Dean Johnston's death to come forward.

He said: "Members of the public can call Crimestoppers with potentially valuable information about any crime without leaving their name or personal details.

"The ability to give information anonymously can be an important incentive and could help solve a case and secure a conviction."