The boyfriend of a New York teenager who disappeared on spring break in Myrtle Beach said someone knows what happened to her, but he doesn't believe the male friends she visited there are involved.

John Grieco said his girlfriend Brittanee Drexel never told him about the group, including Peter Broswick — whose hotel room she went to shortly before she vanished the night of April 25.

Detectives believe Broswick may have been the last person to see 17-year-old Brittanee alive.

"She didn't make me aware of that because she was friends with them and she knew that I didn't necessarily like the fact that she was hanging out with a whole group of guys," Grieco told FOX News on Tuesday.

But Grieco said he doesn't think Broswick is involved in whatever happened to his girlfriend.

"I don't believe he had anything to do with Brittanee's disappearance," Grieco said. "I do believe there are people out there who know what happened to her."

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When asked whether Brittanee could have hurt herself or left of her own accord, Grieco said "absolutely not."

"This is not a runaway case, and she did not do anything to harm herself," he told FOX.

Police released new surveillance footage late Monday of the Rochester, N.Y., high school junior going to the Blue Water Resort Hotel to visit Broswick and the group of boys he was staying with along Myrtle Beach's popular Ocean Boulevard strip.

Meanwhile, Brittanee's mother thinks her daughter could be dead after going on the spring break trip against her wishes.

Dawn Drexel told WHEC News 10 in Rochester that her daughter would never run away.

"I seriously think someone took my daughter or she may not be alive," Dawn Drexel said.

Brittanee Drexel, a junior at Gates-Chili High School, left the Bar Harbor Hotel, where she was staying with some girl friends, at about 8 p.m. on April 25 to visit Broswick.

Broswick, who is also from Rochester, left Myrtle Beach to return home to New York about 1 a.m. the night Brittanee was last seen, according to News Channel 15's CarolinaLive.com.

He and several others were questioned, but were cleared as suspects, according to Brittanee's mother.

"As far as I know, they’ve done what they needed to do as far as those boys are concerned back home," said Dawn Drexel. "They’re not persons of interest anymore."

South Carolina authorities focused their search over the weekend on an area just south of where the teen disappeared after pinpointing the last place her cell phone gave off a signal.

Brittanee's cell phone signal was captured April 26, a day after police say the teen was last seen. Myrtle Beach Capt. David Knipes told reporters the search hasn't yielded any new clues in the case.

Drexel has said she's concerned because the teen suffers from depression. The girl may have been upset because she and her husband are getting divorced, according to Drexel.

Family and friends spent the past week canvassing popular beach clubs and hangouts in the resort town without any results.

Brittanee has blue eyes and shoulder-length brown hair with blond highlights. She's 5 feet tall, weighs about 100 pounds and was last seen wearing a multi-colored shirt, black shorts and flip-flops.

Those with any information are asked to call Myrtle Beach Police at (843) 918-1300, 1-800-CRIME-TV or 1-800-THE-LOST (843-5678).

Click here to visit HelpFindBrittanee.com.

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The Associated Press contributed to this report.