London (CNN) -- Barclays former boss Bob Diamond was in the spotlight when he was questioned by British parliament's 13-strong Treasury Committee last week, but the rate-fixing scandal which lost him his job looks set to reach far further afield.
Diamond's committee appearance came after British and American regulators fined Barclays more than $450 million for rate fixing during the height of the global financial crisis. But Barclays is just one of a host of banks facing investigation.
Now lawsuits are being prepared in reaction to the rates fixing which may have left banking customers around the world out of pocket.
What happened at Barclays?
Between 2005 and 2009, when Diamond was in charge of the investment branch of Barclays bank, traders were influencing the pricing of rates which impacts up to $800 trillion of securities.
E-mails revealed as part of the rate fixing investigation showed traders were seeking beneficial rates for their trading positions.
During the credit crisis of 2007 and 2008, Barclays high Libor postings came under scrutiny and the bank, concerned about "unfounded negative perceptions," lowered its Libor submissions, according to Barclays notes to the Treasury Committee.
Regulators investigating Libor manipulation last month fined the bank more than $450 million. A report from the UK's Financial Services Authority concluded the issues were of the "utmost seriousness" owing to the prevalence of rates references throughout the markets.
But Barclays is unlikely to be the only bank facing financial penalties. Several additional banks are cited but not named in documents made public as part of Barclays settlement with the FSA.
Deutsche Bank, Royal Bank of Scotland, Credit Suisse, Citigroup, JPMorgan Chase and UBS are among the banks that are acknowledged as being investigated by regulators.
Why is Libor so important?
Libor, or the London Interbank Offered Rate, is the benchmark rate which is set every morning by banks posting the rate at which they are willing to borrow with the British Bankers' Association.
The BBA publishes Libor as a result of this, and the rate is then used to fix the borrowings of credit cards, mortgages, car leases and more.
According to Ralph Silva, a former investment banker, the Libor rates for different currencies are directly connected to 99% of all commercial banking products.
Barclays was accused of manipulating its Libor rate for reasons including for the personal benefit of some traders' books.
According to Diamond, other banks struggling during the credit crunch were posting Libor levels significantly below that of Barclays, which he said during Wednesday's questioning "did not seem to us to be right."
Why has this become so political?
The enthusiasm for politicians to wade into the Barclays furor indicates heat will remain on the sector as the investigations into rate fixing continues.
Politicians from both sides of the political fence took jabs at Barclays, with Prime Minister David Cameron saying the manipulation was "outrageous."
Before he came before the committee, Diamond appeared to be ready to point the finger at others for pressuring the bank on its rates. Barclays had released notes of a phone conversation between Diamond and the Bank of England's deputy governor, Paul Tucker, suggesting that politicians wanted Barclays to keep its rates low.
However, during the grilling Diamond deflected suggestions from MPs suggesting he must have known that conversation was misinterpreted by Jerry del Missier, then president of Barclays Capital, as an instruction to lower the level.
Under questioning by MPs, Diamond said his reaction was an appreciation that Tucker was "doing his job" and that Barclays needed to ensure Whitehall -- an all encompassing phrase for British government -- knew the bank was financially stable. Tucker has asked to appear before lawmakers to explain his side of the story.
What will the legal fallout be?
Civil suits are already being filed and others are in train. In the U.S., several law firms are taking class action suits with defendants including Barclays, RBS, Citigroup and Credit Suisse.
One, being pursued by Hausfeld LLP, is on behalf of the mayor and city council of Baltimore, who argue they suffered losses on interest rate swaps as a result of the defendants "anti-competitive conduct."
In the UK, Hausfeld says it is speaking to a number of "potential claimants with a view to bringing an action for damages in the English High Court against Barclays and other banks implicated in the LIBOR rate manipulation scandal."
It is not yet clear if criminal charges could be brought against traders involved in the rates rigging.
What happens next?
MPs are expected to debate if an inquiry should be held into the scandal, potentially through a Leveson-style judge-led investigation.
Investigations into Libor are continuing across jurisdictions including the U.S., UK, and through the European Union. Further high-profile resignations in the banking sector are possible given the precedent set by Barclays.
Regulators are also facing scrutiny. In its statement Barclays claimed it had alerted U.S. and British authorities about suspicious Libor submissions by other banks in late 2008, and was "disappointed that no effective action was taken."
The British Bankers' Association, meanwhile, says it's reviewing the process by which Libor is set.
CNNMoney's James O'Toole and Maureen Farrell contributed to this report