A number of poison pen letters - written by a barrister and targeted at some of Northern Ireland's most senior lawyers - have been seized by police.
Officers were called in after the letters, which make shocking allegations about dealings within the province's legal profession, were circulated within the Bar Library.
The content of the letters, seen by the Belfast Telegraph, has been deemed "defamatory" and "unsubstantiated" by the Bar Council – the body that represents Northern Ireland's 700 self-employed barristers.
The PSNI said that officers were carrying out inquiries to determine if any criminal offence had been committed through the sending of the letters.
The anonymous author alleges within the letters that the Bar Library is one of the most "sectarian, sexist and class driven institutions in Belfast". Other allegations include that some barristers have offered bribes to secure work, a culture of sexist bullying and harassment exists, religious and social divisions are rife, promotions are based on connections, and some lawyers are paid cash in hand.
Claims about the personal lives of some named barristers are also contained within the letters.
The letters were referred to the Law Council's Professional Conduct Committee and their contents were deemed to be unsubstantiated. After attempts were made to circulate a third letter earlier this month police were called in to investigate.
The Bar of Northern Ireland's chief executive, David Mulholland, contacted all members of the Bar Library last week to inform them that the PSNI had been contacted in relation to the letters.
"On the 22nd July 2014 an attempt was made to post an anonymous letter to each member of the Bar Library. The letter was passed to a member of the Professional Conduct Committee who, in turn, passed it to the Chief Executive's Office," Mr Mulholland said in his correspondence with the lawyers.
He added: "The apparent author of the letter is a member of the Bar Library purporting to write the letter on behalf of an unidentified group of barristers at the Bar Library. The allegations contained in the letter are defamatory.
"This follows on from two previous letters which, having been referred to the Professional Conduct Committee, were considered and deemed to be unsubstantiated. This has also been independently verified."
Mr Mulholland also said: "Following receipt of the most recent letter the Bar Council has received independent legal advice that the author/s of the correspondence may have committed a criminal offence. On the advice of senior counsel, contact has been made with senior members of the PSNI and the PSNI have confirmed the criminal nature of the actions undertaken.
"The PSNI have seized a number of letters issued within the library for the preservation of potential forensic evidence."
He requested that anyone in possession of the letter return it and its envelope to him so it can be forwarded to the PSNI.
"If you have taken possession of the letter, you should not copy, disseminate or otherwise publish the letter. It is incumbent upon you to return the letter to me along with the envelope for onwards transmission to the PSNI.
"If you are aware of any of the details surrounding the authorship of the letter or have any information which may assist the investigation you are asked to immediately bring any such information to my attention for onward communication to the PSNI."
In a statement the Bar Council said: "We can confirm a number of anonymous letters have been received to the Bar Library. The matter has been reported to Police and is the subject of a criminal investigation; therefore, we are unable to comment further."
A police spokesman said: "A matter has been reported by the Bar Council to the PSNI and police are currently carrying out enquiries to ascertain if any criminal offences have been committed."