Linda Tripp, whose covert recordings led to the impeachment of former US president Bill Clinton, has died aged 70.
Attorney Joseph Murtha confirmed her death but gave no further details.
Ms Tripp worked in the Pentagon's public affairs office when she befriended Monica Lewinsky, a former White House intern with whom Mr Clinton had an extra-marital affair.
As the pair's friendship developed, Ms Lewinsky detailed her relationship with Mr Clinton.
Ms Lewinsky recorded telephone calls between the pair about that situation - which documented the affair in great detail.
Ms Tripp eventually turned over 20 hours of recordings to Kenneth Starr, an independent prosecutor who was investigating Mr Clinton.
This prompted the investigation which led to Mr Clinton's impeachment.
The House impeached Mr Clinton in December 1998. After a five-week trial in the Senate, senators rejected both articles in February 1999.