St. JOHNSBURY, Vt. » A snowplow driver and his wife went to great lengths to dispose of the body of a popular teacher they had just beaten and strangled, putting her nude body on a tarp, pouring bleach on it, weighing the corpse down with concrete blocks and tossing it into the Connecticut River, court documents allege.

Allen Prue, 30, and his wife, 33-year-old Patricia Prue, were riding around when he got the idea "to get a girl," a police affidavit said. They are accused of luring single mother Melissa Jenkins from her home by pretending their vehicle had broken down. Her vehicle was found idling Sunday with her unharmed 2-year-old son inside. The child apparently witnessed at least part of the attack.

The couple pleaded not guilty Wednesday to second-degree murder in the death of Jenkins, a 33-year-old science teacher at the prestigious St. Johnsbury Academy, and unauthorized burial or removal of a dead body. More charges are possible, police said.

People in the close-knit communities of northeastern Vermont had been speculating about the crime and who was responsible.

"But they didn’t expect the gruesome" details, said a tearful Marion Beattie Cairns, the owner of The Creamery Restaurant, where Jenkins had worked part-time as a waitress and people had gathered since her disappearance to console each other.

Vermont State Police Maj. Ed Ledo said he hoped the arrests would bring closure for Jenkins’ family and friends.

"We can now turn our full attention to healing from this tragic loss, celebrating Melissa’s life and mourning her death," said Joe Healy, a spokesman for St. Johnsbury Academy, which will hold a memorial service for her on Friday. The school counts President Calvin Coolidge among its alumni.

Police said the Prues hadn’t planned a use of force. But they gave few details on a possible motive in Jenkins’ death. The Prues were ordered held without bail.

"They knew Miss Jenkins and had snowplowed her driveway a couple of years ago," Vermont State Police Maj. Ed Ledo said at a news conference announcing the arrests.

A friend told police that Allen Prue had asked Jenkins out a couple of times and that she felt uncomfortable around him, according to the documents. She stopped having him plow, and in autumn 2011 he showed up drunk at her home asking if he could plow her driveway the following year.

After the court appearance, Allen Prue’s mother, Donna Prue, said that her son has never been in trouble with the law before and that she has faith he didn’t commit the crime.

"I do not believe he would ever do this, because he didn’t have it in him. I have nothing against her (Patricia); I don’t have nothing bad to say about either one," said Donna Prue, who lives with the couple and her daughter. She said she did not know Jenkins.

Police were called Sunday night after Jenkins’ son was found alone in her vehicle. Court documents said the boy tried to tell police what happened to his mother by grabbing the back of his neck and saying "mommy cried."

Her former boyfriend told police she called him saying that she had gotten a weird call from a couple who used to plow her driveway and that she was going to help them. She wanted someone to know what she was doing, the documents say.

When he couldn’t reach her two hours later, he went to check on her. He told police he found her vehicle, with her son sleeping in it, and one of her shoes nearby.

Allen Prue later told police that Patricia Prue had called Jenkins and said they were broken down hear her home, documents said.

The police affidavit said:

When Jenkins got out of her vehicle, Allen Prue grabbed her and strangled her. He then put the body in the backseat of their car, and they drove to their home. At some point, Patricia Prue choked Jenkins in the car "to ensure she wasn’t breathing."

Back at their home, he put Jenkins’ body on a tarp, removed her clothes and poured bleach on her body. The Prues also removed their clothes and put them on the tarp.

They then drove to a boat access at the Connecticut River, which separates Vermont from New Hampshire, and put Jenkins’ body in the water, weighing it down with cinder blocks and concealing it with brush.