Riley Strain's fraternity brothers 'heartbroken' as search in Nashville continues, his mom says

The fraternity brothers who were with Riley Strain on the night he vanished in Nashville, Tennessee, are "heartbroken" as the search for the 22-year-old continues, Strain's mother said.

"We love these boys like our own," Strain's mom, Michelle Whiteid, said through tears at a news conference Tuesday. "It's just as hard on them as it is on us."

"We're just focusing on bringing Riley home," she said. "He's my best friend."

MORE: College student Riley Strain missing in Nashville: A timeline

Strain went missing on March 8 after a night out in Nashville.

Strain and his Delta Chi fraternity brothers from the University of Missouri were in Nashville for their fraternity formal and went out in the city's Broadway area. Surveillance cameras and police body cameras captured Strain's last known movements from about 9:30 p.m. to 10 p.m.

Authorities have been searching by foot, by drone and by boat, including using boats with sonar equipment, according to police.

The United Cajun Navy has also arrived in Nashville to help. David Flagg of the United Cajun Navy said they're searching the river and are putting together a "structured and organized ground search."

As Nashville residents volunteer to help, Flagg warned that it's "steep and treacherous terrain on the riverbank."

MORE: New video shows missing student Riley Strain briefly speak with police on night he vanished in Nashville

"Our main focus, obviously, is to find Riley. Our secondary focus is to ensure the safety of the people who are out here searching," he said.

On Sunday, Strain's bank card was found on the embankment between Gay Street and the Cumberland River, near Riverfront Park, police said.

But Nashville Police Sgt. Robert Nielsen stressed there's still no evidence of a crime.

"One of the concerns people have called in multiple times about [was to say] Riley was being chased, he was being followed -- we have seen no evidence of that," Nielsen said.

"We've been through the video multiple times, and that is the reason we released that body camera footage [of Strain's brief interaction with an officer at about 10 p.m.] Because that officer had an interaction with him," he said. "And we've talked to other people who have indicated to us there was no injuries on Mr. Strain ... no indication he was running from anything."

"Our goal is still to bring Riley home," said Strain's stepfather, Chris Whiteid.

Flagg said anyone looking to volunteer in the search can sign up at unitedcajunnavy.org.

Riley Strain's fraternity brothers 'heartbroken' as search in Nashville continues, his mom says originally appeared on abcnews.go.com