OAKLAND – Police on Thursday labeled Tuesday’s death of a 21-year-old Colby College student a homicide, saying it appears she may have been abducted from a campus parking lot and then killed less than a mile down the road where police found her abandoned car and her body a short distance away.

If the size of the investigation under way indicates the level of concern among investigators, then the concern is great.

“People should use safety precautions that they always should use, such as not walking alone, locking their car doors. We are all taught these rules as children, but they absolutely apply now,” said Waterville Police Chief John Morris.

Around the Colby College campus, security was being tightened with assistance from Waterville Police. The 1,830 students were being urged to be vigilant.

Maine State Police Lt. Timothy Doyle said detectives believe that Dawn Rossignol of Medway left her dorm room on the college campus at 7:20 a.m. and proceeded to her car in a satellite parking lot nearby.

Relatives said Rossignol’s purse was found in the vehicle, possibly ruling out robbery as a motive for the slaying. They also said that Rossignol did not have a boyfriend that they knew about.

Doyle said police believe Rossignol was killed “between the time she left her dorm at 7:20 until 9 a.m. when we think we have someone who spotted her car at the Rice Rips Hydro plant.”

Police refused to release how Rossignol was killed, a common decision when the killer remains unidentified. They also did not reveal whether the young woman was sexually assaulted.

“We are looking for anyone who may have seen anything between 7:20 a.m. and 9 a.m. Tuesday,” Doyle said during a late-afternoon news conference in Oakland.

Doyle said investigators believe Rossignol was abducted because the area where she and her car were found were not along the route that she would have been traveling. Rossignol had left the campus with plans to meet her mother, Charleen Rossignol of Medway, in Bangor where Dawn Rossignol had a doctor’s appointment that day.

Her parents reported her missing when she failed to show up.

Doyle said Rossignol would have taken a completely different route, down Washington Street toward Interstate 95, instead of along the Rice Rips Road located in the opposite direction.

A police officer helping with the search for Rossignol spotted her car at 11:30 a.m. Wednesday on a small dirt road leading down to the hydro plant located along the banks of Messalonskee Stream. Her body was found about 300 feet in front of the car.

The size of the search for evidence on Thursday was stunning and spoke to the seriousness the investigation has taken on as police from several agencies sought Rossignol’s killer.

Two busloads of cadets from the Maine Criminal Justice Academy in Vassalboro were being used to conduct line searches of the crime scene and were posted throughout a milewide area, seemingly to prevent people from disturbing possible evidence.

Dozens of game wardens from the state Department of Inland Fisheries and Wildlife used the area by the Thompson and Hachey Self-Storage Co. located near the crime scene as a base of operations for their role in helping to search for evidence.

A military helicopter hovered overhead, searching for anything out of the ordinary on the ground.

“We are looking for anything at all, a discarded coffee cup, anything at all that could potentially be evidence in this crime,” said Lt. Nathaniel Berry of the DIF&W.

The Maine State Police mobile crime unit, in the form of a huge motor home, was parked in front of the Colby College campus with detectives inside waiting to hear from anyone, including students who may have seen anything unusual Tuesday morning.

Students drifted in and out of the unit throughout the day on Thursday.

The presence of the crime unit on the picturesque and quiet campus was surreal as the bells from the campus clock tower competed with the thrumming of the military helicopter flying nearby.

The search seemed to be focusing on the mile or so area between the campus and the hydro plant and rural residential area to the north of the hydro plant. The search area included the stream and much focus seemed to be on railroad tracks in the area.

Meanwhile, on campus, students remained subdued about Rossignol’s death and concerned about the safety of the campus.

“The mood is quite somber,” said Colby Spokesman Stephen Collins. “Right now we are trying to make sure we provide for the emotional and physical needs of the students and to reinforce safety and security issues.

“We really can’t be reassuring with all of this uncertainty out there,” he said.

Colby President William D. Adams decided to hold a news conference on campus Thursday night after learning what came out of the police news conference earlier.

“I know this terrible news will cause deeper anxiety in our community, especially since no one has been arrested in connection with Dawn’s death. It is extraordinarily difficult to cope with this kind of uncertainty. … Now is the time for us to be especially vigilant,” Adams said.

Adams said he had received some calls from parents but found most of them were very supportive of the administration’s level of communication with the students during the difficult time.

The college Website is filled with letters to the students from the president and from the chief of security and safety tips are also available online.

Adams said classes and campus activities were going on “as normal as possible, because we think a disruption in routine would increase the anxiety. But there is this incredible level of sadness and disbelief.”

Earlier in the day, Kaitlin McAfferty and Kate Russo, both Colby seniors who work at the campus newspaper, said that students were scared.

“Everyone is very anxious that this happened in the Colby bubble, where we always felt so safe,” said McCafferty.

Rossignol was a senior biology major. She graduated from Schenck High School in 2000 as valedictorian of her class.

Doyle said there is no connection between Rossignol’s death and that of a 65-year-old man found shot to death in his front yard Monday in the town of Moscow, roughly 40 miles from Oakland.