When police first encountered the 7-year-old girl around 4 a.m. Sunday, she was soaking wet, bruised around the neck and still wearing her pajamas.

Even more dramatic was the story of survival she recounted to officers — of being kidnapped, strangled and tossed off a bridge but somehow swimming to safety.

Now, investigators in Worcester, Mass., are trying to piece together how the 7-year-old found herself plummeting into Lake Quinsigamond in the middle of the night — and why.

Authorities have not released the name of the girl. On Monday, police said in a news release that they have arrested 35-year-old Joshua Hubert, who lives in the city, 50 miles southwest of Boston. A police spokesman directed questions to the district attorney’s office.

Hubert is charged with kidnapping, although prosecutors have said there is a “strong likelihood” that other charges will be brought as the investigation continues, prosecutors said.

Meanwhile, Hubert was being held in jail until a Thursday hearing at which a judge will determine whether he would pose a danger to the public if released before trial.

The incident started Sunday morning on Forestdale Road, where the girl’s grandparents had hosted a cookout, police said. Hubert was a guest at the party, according to Paul Jarvey, a spokesman for the Worcester County District Attorney’s Office.

The 7-year-old was asleep in a chair when, police say, Hubert grabbed her and put her in a car.

In the car, he choked her and drove toward Lake Quinsigamond.

The girl was thrown from the Interstate 290 bridge spanning the lake, according to Worcester ABC affiliate WCVB.

The bridge is one of three that crosses the body of water, which is popular with boat-racing enthusiasts and is the site of several summer regattas, according to the Worcester Telegram.

After the girl was tossed over the side, police said, “she survived the drop and swam to shore.” A fall from the bridge could be fatal. A 19-year-old man who jumped from there in 2012 died, the Telegram reported.

About 90 minutes after the girl disappeared from her grandparents’ house, she knocked on someone’s door in neighboring Shrewsbury, which is on the other side of the lake. That person called police.

The girl’s injury — contusions on her leg and wrists, and marks on her neck consistent with being choked — were not life-threatening.

Hubert’s appointed attorney, Richard Welsh, said the defendant will plead innocent. Welsh did not respond to an email or a phone message left by The Washington Post on Monday afternoon.

Police have not detailed what was going on at the cookout in the moments leading up to the incident. The Department of Children and Families is investigating, Jarvey said.

Also still hazy: Why police think the suspect grabbed the girl in the first place.

“Fortunately, a greater tragedy was averted,” Worcester County District Attorney Joseph Early Jr. said in a news release. “The young victim had the strength to make it to shore and get help. I want to thank the resident who answered the door and helped the girl.”

Read more: 

A 3-year-old was killed in a road-rage shooting while shopping with his grandmother, police say

A backpack, a Coke bottle and fake cocaine: Inside a Border Patrol agent’s smuggling arrest

‘I’m going to hit him’: Dash-cam video shows officers tried to run over man before shooting him 14 times

A white officer said she was shot by a black man. Then her story started to unravel.