Britain's Serious Fraud Office (SFO) said on its web site Tuesday that it's decided to open a criminal investigation into the allegations made by Hewlett-Packard about the circumstances surrounding the sale of Autonomy to HP in 2011. But first it's got to figure out if it's in conflict of interest.

See, the SFO uses an Autonomy product called Introspect as a document management tool. The SFO says it's "keen to ensure that there is now no conflict of interest, or perception of such a conflict and it is obliged as a first step to make inquiries to ensure that it can continue as the investigating body. It is undertaking this work at present."

It also said it wouldn't have anything to say while the investigation is underway. And that could reportedly take four-six years.

The Justice Department, the SEC, the FBI and the UK's Financial Reporting Council are already investigating HP's claims of improper accounting, "disclosure failures" and outright "misrepresentations" by Autonomy prior to its acquisition, which caused HP to overpay for it.

HP wrote off $8.8 billion of the $11 billion purchase price late last year. It attributed $5 billion of the write-off to Autonomy's accounting practices, including premature or improper revenue recognition.

Former Autonomy CEO Mike Lynch and former CTO Sushovan Hussain, who have retained separate high-profile criminal lawyers, have denied HP's accusations.

HP chairman Ray Lane and other board members who voted in favor of the Autonomy acquisition are under attack for not doing due diligence.