A former special constable with South Wales Police sent herself letters filled with white powder at the height of the anthrax terrorism alert.
The letters were sent at the height of the anthrax terrorism alert
Andrea Thomas also admitted calling on police to investigate a series of malicious calls she was found to have made herself.
The 32-year-old, of Mayhill, Swansea, was working as a civilian desk clerk at the time.
She was bailed and will be sentenced at Swansea Crown Court on 15 October.
The court heard on Friday that Thomas was now seeing a psychiatrist who had been unable to fathom why she had acted as she did.
Thomas sobbed as she was led to the dock and eventually became so upset she was permitted to sit while giving her pleas to a series of charges.
She pleaded guilty to one charge of committing acts intending to pervert the course of public justice.
Time and money
The charge, which covered a period from June 2003 to February 2004, was subdivided into six sections reflecting the full extent of her actions.
The court heard she sent herself threatening letters and made telephone calls to herself of a malicious nature.
She also persuaded a man called Paul Kelly to make malicious telephone calls of a malicious nature.
She complained to police about receiving malicious calls knowing it would cost time and money to investigate them and suggested and identified individuals as a possible suspect knowing they could be at risk of arrest.
Thomas denied four separate charges of making hoaxes and threats involving noxious substances between December 6 2003 and January 21 2004.
Kevin Riordan, prosecuting, said since count one covered sending herself letters he was content to let the other four charges lie on file.
He said the letters had been sent "in the middle of the anthrax scare world wide when there was great fear about postal deliveries which were noxious."
Nicholas Gareth Jones, defending, said that Thomas had been suffering from depression at the time and was now seeing a psychiatrist.
"He has been unable to clarify what her motivation was in acting as she did," he told the court.
He asked for a psychologist's report on her case in the hope it would "get to the matter that a psychiatrist could not".
Judge Michael Burr granted a bail and a three-week adjournment until 15 October when Thomas will be sentenced.