Five years after it started, federal prosecutors have ended their investigation into U.S. Sen. Robert Menendez's relationship with a nonprofit agency in Hudson County.

The Star-Ledger of Newark reports no charges will be brought in the matter, which became public during the Democrat's bid for his first full term in 2006.

The newspaper cited a letter sent to Menendez's lawyer by Zane David Memeger, U.S. Attorney for the Eastern District of Pennsylvania, whose office took over the probe in 2009 when Paul
Fishman was appointed U.S. Attorney for New Jersey. Fishman recused himself to avoid a potential conflict of interest, because Menendez
had supported him for the federal post.

"After review and consideration of the matter transferred to
me, I have decided to close the file," Memeger wrote in the Oct. 5
letter, co-signed by Assistant U.S. Attorney Richard P. Barrett. It
indicates that Menendez's lawyer, Marc Elias, had called Memeger to
seek an update on the investigation, though prosecutors typically
don't respond to such requests.

The newspaper did not say how it obtained a copy of the letter,
which does not explicitly say Menendez has been cleared of
wrongdoing. But one expert told the newspaper that it amounts to a
"de facto exoneration" because prosecutors rarely send out such
letters to people being investigated.

Menendez declined comment on the conclusion of the
investigation, which focused on his relationship with the North
Hudson Community Action Corp., an anti-poverty group that he helped
secure millions of dollar in federal funding.

The agency rented office space in Union City from Menendez, who
collected more than $300,000 in rent from the agency between 1994
and 2003 while serving in the House of Representatives. He was
later appointed to the U.S. Senate seat that Jon Corzine vacated
when he was elected New Jersey's governor in 2005.

Menendez said at the time that the rental agreement had been
preapproved by the House ethics committee, and he maintained it was
appropriate. But during the 2006 senate campaign, when he was
challenged by GOP state Sen. Tom Kean Jr., Republicans used the
issue to question Menendez's integrity.

The Democrat accused then U.S. Attorney Christopher Christie -- a
Bush-appointed Republican who went on to defeat Corzine for the
governor's chair in 2009 -- of playing politics by publicizing the
federal probe in the midst of a heated election, a charge Christie
strongly denied.

Menendez went on to easily win the 2006 election and will likely
seek re-election in 2012.