The Senate Ethics Committee declined today to investigate Louisiana Senator David Vitter, who was linked to an escort service whose owner was convicted in federal court and subsequently committed suicide.

The committee says it declined to pursue the case because Vitter's conduct preceded his Senate service, did not result in charges against him and did not involve use of his public office or status for improper purposes.

In a letter to Vitter, the committee also took note of the first term senator's July 2007 statement when he said, ``This was a very serious sin in my past for which I am, of course, completely responsible.''

Vitter has acknowledged that his Washington phone number was among those called several years ago by the escort service run by Deborah Jeane Palfrey. Palfrey committed suicide earlier this month, saying in notes that she couldn't bear going to prison.

The senator was spared further embarrassment when he was not called as a witness in Palfrey's trial. She was convicted of money laundering, using the mail for illegal purposes and racketeering.

The committee of three Democrats and three Republicans said it made no factual findings on Vitter's conduct. The senators added that their dismissal "should not be taken as personal ... acceptance'' of Vitter's actions. And the committee said it reserved the right to reopen an investigation if new allegations surface.

The complaint seeking an investigation was filed by a congressional watchdog group, Citizens for Responsibility and Ethics in Washington. The organization's deputy director, Naomi Seligman, said, ``The Senate ethics committee has once again done what is does best: nothing.''