Three weeks after vanishing into the night, there’s no sign of college student Shane Montgomery. It’s a mystery chipping away at hope the 21-year-old’s family has been holding onto with each passing minute.

"I’m not going to lie anymore. It’s pretty bad with the holidays here," Kevin Verbrugghe, Montgomery’s uncle, told NBC10 Thursday morning.

"We’re not holding up well," he said.

Montgomery was last seen early Thanksgiving morning as he left Kildare’s Irish Pub along Main Street in the Philadelphia neighborhood of Manayunk. Pings from his cellphone put him within a mile of the bar within an hour of his disappearance and surveillance video shows the West Chester University student walking toward the Manayunk Canal and Schuylkill River. Despite many searches on land, in the water and from the air, there have been no strong leads as to where Montgomery went.

"It’s obviously horrible for the family because they have nothing," FBI Supervisory Special Agent J.J. Klaver said.

Wednesday, an FBI Evidence Response team based out of New York went back into the water with more sophisticated equipment, to look for Montgomery. They attempted to use sonar, but the river is too shallow for it work properly. Underwater cameras did work, but did not turn up anything promising, Klaver said.

"The prevailing theory is that he went into the river and where is he now? Tides change and there’s all kinds of debris under there," he said. If Shane’s body is in the river, he could be trapped under the debris, the agent added.

Philadelphia police also launched a helicopter for another air search Wednesday and the Pennsylvania State Police sent a cruiser to conduct another ground search in the area around the Green Lane bridge, Verbrugghe said. Neither were fruitful.

Klaver said while the FBI will continue to assist Philadelphia police on the case, without new leads, they will soon have to begin pulling back their efforts.

Montgomery’s family is not giving up.

They have reached out to the Garden State Underwater Recovery Unit, a volunteer diving recovery team based out of New Jersey, asking for their help in conducting another underwater search, according to Verbrugghe.

A reward for information that leads investigators and the family to Montgomery still stands at $65,000. Friends and family continue to support the search efforts on their own as well. A run to raise money for the effort will take place Saturday and on Sunday there will be a rosary prayer service at St. John the Baptist Church.

The support from the public and law enforcement is what keeps the family going, the uncle said.

"In this bad tragedy, the love and support that we’ve gotten is just incredible,” he said. “We appreciate how everything that they’ve done. All the prayers, all the thoughts, all the help and love.”

Anyone with information is asked to call Philadelphia police at 215.686.TIPS.

Contact Vince Lattanzio at 610.668.5532, vince.lattanzio@nbcuni.com or follow @VinceLattanzio on Twitter.