Guandique, 29, was convicted of two counts of first-degree murder for attacking Levy while she was jogging alone in Rock Creek Park in May 2001. Her body was discovered a year later.
Guandique could get a minimum of 30 years and a maximum of life in prison. His sentencing hearing has been set for Feb. 11.
The Levy case destroyed the political career of former Democratic Rep. Gary Condit, 62, who testified in the trial that he and Levy, 24, were on good terms at the time she went missing. He declined to respond to questions about whether the two were romantically involved.
Though Condit was never an official suspect in the case – authorities questioned and cleared him after Levy's disappearance – the congressman's reported relationship with the Washington intern caused a firestorm of sensational headlines around the globe.
After the verdict was announced Monday, Condit's attorney Bert Fields told PEOPLE, "Finally Gary Condit can get some closure and vindication, but the vindication comes a little late. Who gives him his career back?"