Police investigating the chilling execution of two people in a suburban home are renewing the four-year hunt for the murder weapon this morning after a tip-off.

Specialist dive teams plan to trawl the Regents Canal in Tower Hamlets in an attempt to find the gun used to kill Jordan Jackson and Leyla Djemal-Northcott in Upper Norwood in March 2006.

Masked gunmen burst into 20-year-old Mr Jackson’s flat in Menlo Gardens at about 6.40am, killing him and Miss Djemal-Northcott and injuring Mr Jackson’s brother Keiran by firing at least six shots.

The men ran from the scene and although arrests were made at the time, detectives are yet to solve the murder.

Police believe Mr Jackson, 20 was killed in a pre-meditated execution aimed at him and his brother, and that 21-year-old Miss Djemal-Northcott was an innocent bystander murdered purely because she was in the flat at the time.

Detective Chief Inspector Neil Hutchison, Trident said: “Today our dive search team will be trying to find the weapon as we have received new information that it may have been discarded in this area. This weapon could be the key to solving these murders.

“I believe these murders were pre-meditated executions.

“The two suspects forced their way into the flat early in the morning before shooting the victims at close range. The victims had no chance to run or defend themselves. “ Miss Djemal-Northcott’s mother, Christine Djemal, said: “Leyla has not had the opportunity to finish college, get married, have children.

“She is deeply missed by her family who still find it hard to come to terms with her sudden and violent death."

Jordan's mother said: “Jordan is sorely missed. Due to his untimely death he has missed the birth of his twin brother's son, a nephew he will never see, who is now four years old.

“He never got to see his baby sister's first day at school.

“He was a caring, considerate and loving son, brother and uncle and a joy to be around. He is missed dearly and his murder has destroyed our family. We appeal to anyone who has any information to come forward."

The police are offering a reward of up to £20,000 for information which leads to the arrest and conviction of the people responsible for the murders of Jordan and Leyla and the attempted murder of Kieran Jackson.

DCI Hutchison said: “This happened nearly five years ago but I am hopeful that someone may come forward with information in relation to these murders - allegiances may have changed in the last five years and any information could help us to finally bring those responsible to justice.

“If anyone out there is reluctant to tell us what they know because they are frightened then I want to assure them that they will be protected.

“They can be provided with anonymity in a court case.

“Trident has extensive experience in witness protection and anonymity and has used it successfully on many occasions.”

Claudia Webbe, Chair of the Trident Independent Advisory Group, said: “I appeal to mothers, girlfriends, sisters in the community who must understand the grief Leyla and Jordan's family are suffering.

“Do you have information that could help a mother finally find closure? I would urge them to contact the police and help us ensure that these violent criminals do not cause more pain in our community.”

Anyone with information is asked to call police on 020 8247 4553, or Crimestoppers anonymously on 0800 555 111.