Former LSU kicker Josh Jasper caused a stir when he tweeted that Mathieu had already transferred to McNeese State, where he could play immediately, but that is not the case, sources said.
Mathieu did visit McNeese State on Friday night, Cowboys coach Matt Viator told GeauxNation's Gary Laney. However, Mathieu left without a commitment.
"It's very important for both us and Tyrann to make the right decision and Tyrann agreed," Viator said. "It was a long day. We both needed to back off a bit and make the best decision. Especially him. He needs to catch his breath and make sure he makes the right decision."
Mathieu also is considering Jackson State and Prairie View A&M after ruling out Southern because he wants to leave Baton Rouge, La., The Times-Picayune reported.
"Prairie View A&M is honored to be mentioned in the running for a student-athlete of Mathieu's caliber due to some connections our program and university has with him," the school said in a statement. "As of this time, Mathieu has not met with head coach Heishma Northern in regards to joining our football program but we would be interested once we receive the proper clearance and paperwork needed to talk with him in-depth."
Mathieu has two years of eligibility left and could transfer, but he would have to sit out this season if he went to another school in major college football. If he moved down a level, to FCS, he could play right away.
McNeese State plays in the Southland Conference, while Jackson State and Prairie View A&M play in the Southwestern Athletic Conference.
Meanwhile at LSU, there was a sense among the Tigers that 24 hours after Mathieu was dismissed the focus was very much back on football.
"I thought today was normal," said LSU lineman Josh Dworaczyk of Saturday's long scrimmage. "We got out there and did what we had to do in a scrimmage where we got better. I certainly didn't notice any difference with the team, the morale, anything like that. I think we went out with the same emotions we always have in a scrimmage.
"We were flying around. The special teams flowed nice. At the end of the day, we are mending this wound right now and we are redirecting where we want to go."
To replace Mathieu at corneback, LSU coach Les Miles said Jalen Mills, a somewhat unheralded true freshman recruit, started with the first team defense Saturday in a mild surprise, given that redshirt freshman Jalen Collins emerged from the spring as the Tigers' third cornerback behind Mathieu and Tharold Simon.
"You've got a kid fresh out of high school trying to guard James Wright, Odell Beckham, Russell (Shepard), all those guys, you're going to go right at him," Mettenberger said. "That's how he's going to get better."
As for who will might fill Mathieu's leadership role, Mingo said, "a lot of guys."
"You don't have anybody who does all this," Mingo added, smiling and waving his arms to mimic Mathieu's demonstrative and vocal leadership style. "But we have guys who can lead."
Asked if there was a past experience that could prepare him to help his team get past this adversity, Miles didn't hesitate.
"Yeah, oh, yeah, that first fall Katrina hit (in 2005), I just couldn't hardly believe that one," he said. "And then we lost to Tennessee in Tiger Stadium Monday night. That, right there, prepared you for just about any natural disaster you can imagine. We were up 21-0 at halftime and then lost (30-27). If we'd have hit the field goal before halftime, there's no way they come back.
"So yeah, there are some things in my background that prepare me for this."
Mathieu's dismissal from the LSU program on Friday came after the cornerback's repeated violations of LSU's substance abuse policy for athletes, a source with knowledge of the situation told ESPN.com.
Mathieu was suspended for a game last year for failing a drug test, and he had been undergoing counseling throughout the spring and summer, the source said.
At a news conference on Friday, Miles said Mathieu's dismissal was for violating team rules.
Last season, Mathieu, nicknamed Honey Badger, was a surprise finalist for the Heisman and won the Chuck Bednarik Award as the nation's best defensive player.
The junior defensive back helped the Tigers win the SEC championship and reach the BCS title game, where they lost 21-0 to Alabama.
LSU enters this season ranked No. 1 in the USA Today coaches' poll. The AP college football poll will be released Aug. 18. The Tigers opened preseason camp last week as one of the favorites to reach the national championship game again. LSU started closing practices on Wednesday, but officials said Mathieu practiced at every practice until Friday morning, when he was informed of his dismissal.
Information from ESPN.com's Chris Low, GeauxTigerNation's Greg Laney and The Associated Press was used in this report.