The fire alarm that sounded at 10 Amistad St. on the day Annie Le GRD ’13 was murdered had nothing to do with her death, New Haven Police Department Chief James Lewis said Monday.

In a wide-ranging interview in his office at police headquarters, Lewis said authorities have uncovered no evidence to support the theory that the alarm was set off by the person who strangled Le to death or by an accomplice. The special agent in charge of the Federal Bureau of Investigation in Connecticut, Kimberly Mertz, told reporters two weeks ago that the alarm was triggered by steam from a laboratory hood. The steam may have been released by a person in the lab, Mertz said.

But Lewis said “fire alarms go off in buildings all over the place” and, he added, “I suspect in labs it’s not unusual at all.”

The chief also said that Le’s accused killer, Yale animal lab technician Raymond Clark III, is likely to remain the only person arrested in connection with her murder.

Still, Lewis cautioned that leads from any of the 300 pieces of physical evidence authorities have gathered could lead investigators in new directions. He added that detectives and state forensics lab investigators are still working on the case and may continue to do so for some time.

“You never know where physical evidence might take you,” he said. “Even at trial something may pop up that we don’t know about. But at this point we don’t anticipate any other arrests.”

Whether or not the case goes to trial is still anyone’s guess; after all, Clark has not yet entered a plea. Lewis, for his part, said the legal proceedings could drag on for months.

“There’ll be the standard hearings, but you could have lots of delays,” he said. “I mean this thing may not go to trial for a year or so. There’s just no telling.”

Lewis said he was not surprised that it took five days for law enforcement officers — assisted by bloodhounds from the Connecticut State Police — to find Le’s body.

The research facility at 10 Amistad St. where Le’s remains were discovered last Sunday is a “unique building,” Lewis said. He added that the dogs had a difficult time finding scents of Le because of chemicals in the basement of the building and because “the air flow systems are different than in most buildings.”

Police tracked every person who had access to the basement until they narrowed in on Clark as the lead suspect, Lewis said.

Lewis also revealed for the first time that dogs were not allowed to enter certain areas of the basement because of ongoing experiments involving animals in those rooms. Instead, they were searched by hand, slowing down the investigation, though it was ultimately a dog who found Le’s body in a mechanical chase.

But Lewis would not say that Yale could have done more to prevent the tragedy.

“I think if you did a comparison with most buildings in this town or any town, you’d find a lot of buildings don’t have any surveillance cameras, don’t have any ID cards, really are pretty wide open,” he said. “You could always say Yale could add 10 more cameras, but really to make that jump you’ve got to compare it to any place else. And I think that’s a really secure building compared to any other place. There really is no environment you can make where nothing would ever happen.