Cheerleader murdered by Ex Boyfriend and his wife.

A two-day search for a popular South Carolina high school student ended Saturday with the discovery of the teenager's body in a local river and the arrest of a married couple who police say killed the teen and set her car on fire.

A student spotted the body of Marisha Jeter, 16, as she took photographs near the Broad River. Jeter had been stabbed in the neck, Union County Public Safety Chief Sam White told ABC News.

Jeter, who was president of the junior class at Union County High School and was also a cheerleader, had been last seen Thursday night on her way to McDonald's. She was reported missing early Friday morning by her father, a member of the Union County School Board, after he spent the night driving around looking for her.

Jeter's family told police that Marisha had recently been in touch with Pernell Clayton Thompson, a 20-year-old from neighboring Jonesville, whom she'd been in a relationship with. Thompson had recently married and had a child with another women, Yolanda Lee Thompson, 19.

White said Public Safety officials interviewed the Thompsons individually, both of whom said that they knew nothing about her disappearance.

"He more or less said he didn't know where she was and he would help us find her," White said. "He said that they had a relationship and it went sour, but he didn't give us too much detail."

By Saturday morning, the state police had joined the investigation, and that afternoon, Jeter's body was found about 15 miles from Union at the bottom of a steep river embankment. The photographer used her camera to zoom in and then realized she was looking at a body.

Immediately, police contacted the Thompsons a second time. "We told them during questioning what we found and presented them with information," White said. "They both confessed."

Both were charged in the murder of Jeter and are being held at the Union County Detention Center. They will make their court appearances next week, White said. The pair has apparently never been in trouble with the law before.

Investigators said the fatal confrontation began when Jeter received a text message Thursday evening from Thompson to meet her at the Union YMCA to return a coat. When Jeter arrived, however, she was met by Thompson and his wife, Yolanda, who had discovered that her husband was still communicating with Jeter.

There was a struggle, White said, and Jeter was stabbed in the neck. "They put her in the trunk of her car and drove her car down to Lockhart," he continued, where the body was dumped into the river. The car was driven a few miles down the main road, doused with gasoline and set on fire.