Authorities on Wednesday dropped the murder case against Seiha Srey, saying too many doubts had been raised to expect a jury to convict him of killing another teen-ager in the parking lot of Denny’s Restaurant two years ago.

The Attorney General’s Office dismissed the indictment against Srey without prejudice, meaning it can seek to re-indict him if investigators can put together a stronger case. But Srey’s lawyer, Daniel Lilley, said that’s very unlikely, calling the decision to dismiss “not even a close call.”

Srey spent 19 months in jail while awaiting trial, which was scheduled to open in Cumberland County Superior Court next week.

Investigators say they have been stymied in their efforts to build a solid case by reluctant and deceptive witnesses to the fatal stabbing of Robert Joyal, a Gorham High School senior.

Police say they still consider Srey a suspect, but they must focus the investigation on other potential suspects. Police must either confirm that others implicated in the case were not involved or, if they were involved, gather evidence against them.

“Our best evidence in this case continues to point to Srey, ” said Portland Police Chief Michael Chitwood at a press conference beside the Denny’s parking lot where the stabbing occurred. But Chitwood also said police are prepared to charge someone else if fresh information steers the case in a new direction.

A Cumberland County grand jury is currently hearing aspects of the case, Chitwood said, but he would not elaborate.

Srey was 15 when the stabbing occurred. Dozens of youths had gathered at the late-night hangout on Portland’s Outer Congress Street when a brawl broke out, involving several teen-agers.

Joyal was stabbed three times in the back. Srey was arrested a month later based on statements of two witnesses, one who said he saw the stabbing and another who said Srey told her about it.

But Lilley, Srey’s lawyer, said the defense has witnesses who saw the murderer, witnesses who talked to the murderer and witnesses who saw Srey at the time 50 to 60 feet away from the crime scene.

“This is not even a close call. That’s what’s frightening, ” Lilley said.

It is those witnesses that police will now focus their efforts on, Chitwood said. Police evidence against Srey was adequate to arrest him, have him tried as an adult and win an indictment by the Cumberland County grand jury, Chitwood said.

But during the investigation, police learned that inmates in Georgia and Maine said they knew who the killer was and that it was not Srey.

The men want reduced jail time in exchange for their cooperation and authorities continue to work with their lawyers, Chitwood said.

Also, a key witness for the state identified a different killer before changing his story to implicate Srey.

“We’re dealing with people who are incarcerated in prison who were there that night and the veracity of what they’re telling us is what we’re looking into, ” Chitwood said.

Chitwood defended the detectives working on the case and said the investigation has been hampered by uncooperative witnesses.

“Our chief problem has been the unwillingness of some witnesses to come forward and tell the truth, ” he said. “Some have told half-truths. Some have told lies.”

The case was originally scheduled to go to trial in December, but Superior Court Justice Roland Cole permitted a delay to give the state more time to investigate the contradictory information. With questions still lingering this week, the state decided to withdraw its case.

“It is imperative that when this case is ultimately tried, the best case be put before the jury, ” Chitwood said. “We want to make sure all avenues of investigation have been pursued.”

Joyal’s family joined Chitwood at the news conference Wednesday and said while they share the police view that Srey is the killer, they support the attorney general’s decision.

“I believe they have the right guy, or one of the right guys, ” said Robert Myers, Joyal’s stepfather. “I think it’s smart to wait until you can get a conviction.”

Faith Joyal appealed to the youths who were there the night her son was stabbed to come forward with whatever information they have.

“I just want to remind you it’s not too late to make things right, ” she said. “You can still come forward. You can still make a difference, to help us have some closure.”

Paul Gauvreau, chief of the attorney general’s criminal division, would say little about the decision to drop the charges against Srey.

“It’s an open investigation. We’re going to go where the evidence leads us, ” he said, adding that prosecutors cannot comment on evidence “that might jeopardize this particular defendant’s right to a fair trial at a later date.”