Classmate in custody for allegedly killing Ole Miss student Alexandria 'Ally' Kostial: Officials

A 22-year-old Texas man is in custody in connection with the killing of an Ole Miss classmate whose body was discovered over the weekend, authorities said Tuesday.

Brandon Theesfeld was arrested Monday for the murder of Alexandria "Ally" Kostial, 21, according to the Lafayette County Sheriff's Office. He was taken into custody at a gas station in Memphis, police said.

Theesfeld "was a student in the School of Business Administration and has been suspended from the university," school spokesman Rod Guajardo told ABC News via email.

Deputies were on a routine patrol Saturday at 10:30 a.m. when they found Kostial's body in Harmontown, Mississippi, about 30 miles from Ole Miss, according to the sheriff's office.

Her cause of death has not been released.

It was not immediately clear how Theesfeld allegedly knew Kostial, if at all.

Theesfeld, shackled and wearing an orange jumpsuit, made an initial court appearance Tuesday.

He did not enter a plea.

Theesfeld's father, Daniel Theesfeld, told ABC affiliate WFAA: "I’ve spoken to Brandon. I ask that everyone give him the benefit of the doubt that he is innocent."

"I am seeking legal counsel that will be announced in a day or so," he added.

Kostial was from St. Louis and was studying marketing at the University of Mississippi's School of Business Administration, according to the sheriff's office and the university.

She had been attending summer school, according to her father.

Kostial was also a fitness instructor at the campus recreation center and a former member of the Alpha Phi sorority, said Kassidy Desnoyer, her friend from high school and college.

"She spent her summers going on mission trips. She cared about people and just wanted to help," Desnoyer told ABC News on Tuesday. "She was the brightest light I've ever came across."

A statement from Alpha Phi said: "The Alpha Phi community is grieving the loss of Ally Kostial, and we send our deepest sympathies to her family during this incredibly difficult time. We hope that the Alpha Phi sisters who knew Ally best can find peace and comfort as they reflect on the lasting impact she made on the lives of her family members and friends."

"We are truly saddened by the death of Alexandria Kostial," University of Mississippi Interim Chancellor Larry Sparks said in a statement on Monday.

"Ally was a valued member of our campus community," Sparks said. "We extend our deepest sympathy to her family, friends, and classmates, and stand ready to support them during this time."

Before attending Ole Miss, Kostial graduated in 2016 from Lindbergh High School in St. Louis, according to the school district.

"Our hearts are broken for the Kostials, and we extend our deepest sympathies to her entire family during this time," Lindbergh Schools spokeswoman Beth Johnston told ABC News via email on Monday.

ABC News' Marcus Moore contributed to this report.