On Tuesday, Maria Mendez testified that Guandique scared her by writing about a dead girl, NBC Washington's Pat Collins reported. While Guandique was in prison on an assault conviction, he wrote to Mendez that he was in prison because of a dead girl, Mendez testified.
Prosecutors said that amounts to a confession, Collins reported.
Guandique didn't write that he had killed anyone, but Mendez asked him to stop writing her.
Transcripts of phone conversations between Mendez and Guandique revisited Mendez's fear Wednesday. Mendez asked Guandique if he knew that his reference to a dead girl scared her, and he replied affirmatively.
Levy's disappearance made headlines in 2001 after she was romantically linked with then Rep. Gary Condit. He was once the main suspect, but police no longer believe he was involved.
Levy's remains were found after more than a year in Rock Creek Park.