Officials investigating if missing college student Riley Strain was overserved before vanishing in Nashville

The Tennessee Alcoholic Beverage Commission said it is investigating whether missing college student Riley Strain was overserved before he vanished during a night out in Nashville.

Strain, 22, was last seen by friends at 9:52 p.m. Friday after drinking downtown in the city's Broadway area, Nashville police said.

Strain's friends last saw him when he was kicked out of Luke Bryan's bar, one of the friends told police.

"There are no specific rules or statutes that governs escorting out intoxicated patrons from their businesses or providing assistance in getting someone home," the Tennessee Alcoholic Beverage Commission said in a statement. "However, state law prohibits serving alcoholic beverages to someone who is visibly intoxicated. A violation is a class A misdemeanor. The TABC has opened an investigation into this matter to see if any violations have occurred."

TC Restaurant Group, operator and owner of Bryan's bar, called Luke's 32 Bridge, said earlier this week that it's working with police "to provide security camera footage and any other potentially helpful information to aid in the search for Riley Strain. Our thoughts are with his family and loved ones for his safe return."

The University of Missouri senior was visiting Nashville with his Delta Chi fraternity brothers for their formal, his family said.

"He was excited 'cause he was out, and he was sending me pictures at the different bars they were going to," Strain's mom, Michelle Whiteid, told ABC News.

There's no indication of foul play and no indication Strain was in a fight or argument with anyone that night, Nashville police Sgt. Robert Nielsen said at a news conference Thursday.

Surveillance video from a business showed the 22-year-old walking alone as he stumbled down a street at 9:46 p.m. Friday. An additional angle showed Strain running and falling down.

Nashville police released video showing Strain at 9:47 p.m. Friday. In the video, Strain, wearing a two-toned shirt, crosses the street with a group and checks his phone. He then stops and changes directions for a moment before proceeding down the street behind the group.

The last known surveillance video footage of Strain showed him walking north between James Robertson Bridge and Woodland Street Bridge, Nielsen said, adding that no one else was around him.

"At this point, we're kind of back canvasing ... the possible route he may have taken from Broadway ... to look for any other cameras we may have missed, as well as look for any other potential employees at some of these businesses that we can talk to," Nielsen said.

The search for Strain is ongoing.

Authorities are searching by foot, by drone and by boat, including using boats with sonar equipment, Nielsen said.

Investigators are recanvassing for video and speaking to employees at local bars, all of whom have been "extremely cooperative," Nielsen said.

"All of our resources are dedicated toward finding him," Nielsen said.

As the investigation continues in Nashville, a vigil was held Wednesday at Strain's former high school in Springfield, Missouri.

"Riley's such a good kid," Strain's grandmother, A.J. Gilbert, told Springfield ABC affiliate KSPR. "It's wonderful that so many people, they're sharing [the news], hoping to bring him home."

Anyone with information is asked to call Nashville Crime Stoppers at 615-742-7463.