A carpenter testified Monday that he was told to keep quiet about building a deck for Sen. Ted Stevens (R-Alaska) in order to avoid the appearance of impropriety.

In testimony before the U.S. District Court for the District of Columbia, Brian Byrne said he was told by Bill Allen, the former head of the oil-services firm Veco, that "a certain amount of discretion would need to be used."

Under questioning from government prosecutors, Byrne said he was "not really sure" why he was told to keep quiet, "other than the appearance of impropriety is what he was concerned about."

Allen, the government's star witness, could testify as early as Tuesday. The government is trying to establish that Stevens knowingly and willingly hid more than $250,000 in gifts from Veco executives and other associates in order to avoid public scrutiny. Stevens denies all charges, saying he paid all bills that were given to him, including $160,000 in home renovations.

In 2002, Byrne spent 130 hours, at a rate of $30 per hour, to build a ground-level deck at Stevens's chalet in Girdwood, Alaska. The deck was part of a list of extensive home renovations that cost around $188,000 that prosecutors are alleging that Stevens failed to report on his annual financial disclosure forms.

-Manu Raju