It was about 3:30 a.m. Sunday, on a spring break weekend in Daytona Beach, Fla. The streets were quiet, at last, but someone could be heard pounding on motel room doors at the beach-side Atlantic Economy Inn.

Eventually, the knock came to Room 127, where Lance D. Ulland, 18, of Austin, Minn., who was staying with two Florida cousins and two of their friends, told the others to stay put. "I'm closest," he said. "I'll see what he wants."

One quick exchange later and Ulland was dead -- shot in the head with a .45-caliber handgun, Daytona Beach Police Chief Mike Chitwood said.

The alleged assailant, Matthew A. Castro, 28, of Jacksonville, Fla., arrested about 15 minutes later, told police that he had shot Ulland "because of a bad narcotics dealing ... a few days ago."

But the chief doubts that story.

Chitwood suspects, instead, "that Lance got shot in a case of mistaken identity -- and for no other reason than opening the door."

Castro was "on a search-and-destroy mission," Chitwood said. The suspect is either a former Navy sailor or in the process of being dishonorably discharged, the chief said.

On Monday, little could be learned about Ulland. His address as of March 2 was in the 700 block of 10th Avenue SW. in Austin, said Austin Police Capt. Curt Rude. He said there was nothing in Ulland's police record -- no assaults, no disorderly conducts -- that would raise any flags.

Public school records show that Ulland attended Austin High School for about a month before leaving in 2002. It was not known where he may have then gone to school.

Calls left to family members, including a cousin who was in the motel room Sunday, went unreturned Monday night.

According to Daytona Beach police and a family friend, Ulland was in Florida vacationing with his mother, Joan Taft. They arrived Friday morning in Kissimmee, Chitwood said, and his cousins coaxed him to "come with us" to spring break in Daytona Beach, about 90 miles away.

They arrived that afternoon at the Atlantic Economy Inn, a "mom and pop place," according to the chief, where a room, even at the height of spring break, could be had for about $65 a night "tops," he said.

But in addition to being cheap for college students, the "moms and pops" that dot the west side of Hwy. A1A have proven problematic for attracting a criminal clientele, Chitwood said.

On Saturday, about four doors down from Room 127, Castro arrived with three friends from the Navy. They took two rooms.

Sometime between the suspect's arrival and the shooting, Ulland and Castro had a brief conversation on the beach, said Kim Hames, an Ulland family friend acting as spokeswoman. But it was "nothing special," she said, "no argument."

Motive still unknown

On Sunday morning, after knocking on the succession of doors, Castro was alleged to have asked Ulland, "Are you the kid I was talking to in the parking lot?" Chitwood said.

"He said, 'Yeah,' " the chief told the Daytona Beach News-Journal, "and [the gunman] raised the gun and shot him."

In an interview Monday, Chitwood told the Star Tribune that Castro then allegedly kept the gun raised and pointed into the room, leading two others inside to think, "We're dead."He then turns and walks away," the chief said.

Although Castro is now jailed and charged with first-degree homicide, Chitwood said the investigation into a motive continues. In addition to doubts about Castro's drug claim, he said, there are conflicting stories about whether the men had argued earlier.

On Monday, Ulland's mother, reportedly strapped financially, was trying to find ways to get her son's body back to Minnesota, he added.

Chitwood, a former Philadelphia police homicide lieutenant, said that he thought he'd gotten used to seeing senseless gun violence but that he was still troubled by a generation "that has absolutely no respect for human life."

Ulland, he said, was just a young man in Florida enjoying the 80-degree weather: "Who's thinking, 'I'm going to open a door and get shot in the face?' " Chitwood said.