(NewsNation) — The family of Riley Strain, a University of Missouri student who went missing in March and was later found dead in a river in Nashville, still has questions over his death.

Michelle Whiteid, Strain’s mom, says she is bothered by a text message her son sent the last night he was seen.

Strain disappeared March 8 after getting kicked out of a downtown bar while visiting Tennessee with his fraternity brothers.

Earlier that night, Michelle Whiteid said, he sent her a message, saying he ordered a rum and coke that “didn’t taste good.”

Riley Strain’s family talked to NewsNation’s Brian Entin about Riley’s fraternity brothers, his messages about his drink and more in an extended exclusive interview. Not sure how to watch NewsNation? Log in to this web player or go to JoinNN.com to locate us on your TV. 

Whiteid told Strain he probably shouldn’t drink it. He told her, “It tastes like barbecue.”

“I go, ‘Well, that sounds awful,” Whiteid said in an interview with NewsNation. “He said, ‘Well, it sounds good, but it’s not.'”

“Maybe there was something in it that shouldn’t have been,” Whiteid said.

The TC Restaurant Group, which owns and operates the bar, said Strain was asked to leave after being served one alcoholic drink and two waters.

Whiteid and Strain had a close relationship. Just a couple of weeks before, he had let her know that the fraternity’s annual formal was coming up in Nashville and that he was going. The whole day of the trip, he texted her and gave her a heads-up when they got to the hotel.

“He was excited,” Whiteid said, adding that as a mom, she was still nervous about his trip. They were texting back and forth as Strain went out that Friday night, and later, he Facetimed his mom.

The next morning, when Whiteid got up to go grocery shopping, she got a call from his fraternity brother, asking if she had talked to Strain.

“I said, ‘What do you mean, he’s with you? Why would I? What do you mean you can’t find him?'” Whiteid recalled. “(The brother) goes, ‘Well, he’s not in the hotel, and we can’t find him.'”

After telling the brother to call the police, Michelle and Chris Whiteid, Strain’s stepfather, got in the car and headed from Springfield, Missouri, to Tennessee. Ryan Gilbert, Strain’s father, said he also made a seven-hour trip down there. When the family got there later that day, Gilbert said, a police officer was still there finishing up their report.

Strain’s body was found March 22 in the Cumberland River in West Nashville, less than two weeks after he disappeared.

Family members have previously brought up other questions they had about Strain’s death. Chris Whiteid previously told NewsNation that the last-known footage of Strain showed him approaching the James Robertson Parkway bridge fully clothed. When Strain’s body was found, he wasn’t wearing the pants, wallet, or cowboy boots he had on earlier in the night.

This made his family wonder why the belt they knew he was wearing didn’t secure his pants.

“Riley had a swimmer’s body,” family friend Chris Dingman said earlier this month on “Elizabeth Vargas Reports.” “(The belt) would have been snug to him, riding on his hips. … As soon as we found out he had a belt on that night, (it) totally changes the dynamics of why those articles are missing.”

Police say there is no evidence of foul play, and preliminary autopsy determined that Strain’s death was accidental. His parents, though, have ordered a second autopsy.

“One thing that threw the family for a loop was the coroner going on record stating about the lack of water in his lungs,” Strain’s family friend told NewsNation. “Usually water in the lungs means that they were alive when they went into the water.”

Chris Whiteid says he wants to know what happened and that he will continue to look for answers.

“If he fell and truly fell in the water, and you can prove that to me, show me. I’ll accept it,” he said to NewsNation. “But I can tell you from all the stuff that we’ve done as far as search and looking, taking pictures — I don’t feel like it’s really possible that happened. He may have fallen, but someone helped him in the water.”