Court documents show police are searching for evidence that would link an assistant of a slain corporate executive to the killings of the executive, his wife and son, and their housekeeper in a Washington mansion.

The documents made public Thursday show police obtained a search warrant for a vehicle belonging to the 28-year-old assistant. Identifying him by name, the documents state that police are looking for "forensic and physical evidence linking (the assistant) to this offense."

The Associated Press is not identifying him because he hasn't been charged with a crime.

The assistant was a driver for Savvas Savopoulos who told police he delivered $40,000 to the family's house while they were being held for ransom before they were slain last month.

A police spokesman declined to comment Thursday on whether investigators consider him a suspect.