Police and a key witness in an unsolved slaying have hit an apparent stalemate, ultimately slowing down progress in the investigation.

The man, who said the killer in a Calgary drive-by shooting confessed to him, said he will only make a statement in Canada in exchange for protection.

Police, however, want the man -- deported last year to Trinidad for criminality and whom the Sun has chosen not to name for his safety -- to sign the statement with authorities in the Caribbean.

Police spokesman Kevin Brookwell said the man is holding out in exchange for police assisting him with deportation issues, which they have no jurisdiction over, depriving detectives of a potential lead to catch a killer.

"He is using this as part of a ploy to get back into Canada, we really don't want to get ourselves embedded in immigration-deportation matters," Brookwell said.

"We believe he has information which may be valuable and very, very helpful to move an investigation forward.

"He has had four or five opportunities to give this statement and keeps refusing."

The 40-year-old said an acquaintance told him about the drug-related shooting of Tajmmal Paracha, a 26-year-old gunned down while driving downtown in August 2007.

In March 2008, he told RCMP in Edmonton what he knew. Later that month, a Calgary homicide detective asked for the statement in writing.

Shortly after, they learned of the man's impending deportation and urged him to give a statement.

Now, the man said police have been "deceptive and manipulative," using his information to "get him out of the country."

He has since received a pardon for his prostitution- and fraud-related crimes but failed in bids to be readmitted to Canada.

"I will give police the statement in Canada if they make me admissible (to) Canada," he said from the Caribbean.

Police say they cannot offer the man compensation or protection in exchange for helping to solve a crime.