The 18-year-old is wanted over the murder of John Pordage, 34, who was shot in the chest during a roadside confrontation outside a petrol station in Chelmsford, Essex last summer.
Two other teenagers have already been arrested and tried in connection with the murder but it is alleged that Blundell was the one who pulled the trigger.
A European arrest warrant has been issued for Blundell and Crimestoppers are offering £10,000 for information on his whereabouts.
Senior investigating officer Detective Chief Inspector Martin Pasmore, of the Kent and Essex Serious Crime Directorate, said: “We've received information to say he may be using Ibiza as a place to hide, although it is not known where he is at present.
We have also had information to suggest he has friends who regularly visit Ibiza. We remain determined to locate Bradley Blundell and bring him to trial.“
#Reward of up to £10,000 is being offered for info leading to the arrest of Bradley Blundell in connection with the #murder of John Pordage in #Chelmsford.— Essex Police (@EssexPoliceUK) February 10, 2018
It's being offered through independent charity @CrimestoppersUK.
Please watch and #retweet our video: pic.twitter.com/gzl2QDSpeS
“I appeal to Bradley to give himself up. We will never give up searching for him and we are liaising with the National Crime Agency and colleagues abroad to locate him”. “We also have a European Arrest Warrant in place to facilitate his capture and there is a reward via the Crimestoppers charity for up to £10,000 for information leading to his arrest”.
“Bradley and those advising him need to consider whether he should live a life on the run; never knowing whether an arrest is imminent. It makes sense for Bradley to come forward and face trial now. He will of course have a fair trial and have the opportunity to explain what happened from his point of view. I'm not pre-empting any result but the fact is that as a juvenile, if he were to be convicted and sentenced to imprisonment in the near future, he would still be freed as a relatively young man. The day will come when Bradley will face trial. It is very much in everyone's interest to do that sooner rather than later."
To be eligible for the reward of up to £10,000, please contact the Crimestoppers charity 100 percent anonymously. Anyone in the Balearic Islands or Spain who has information about Blundell's whereabouts can call Crimestoppers on freephone 900 555 111 or use the anonymous online form at Crimestoppers-uk.org.