The role played by the technology firm Fujitsu in the Post Office Horizon scandal will come under the microscope this week, with the judge-led inquiry and a committee of MPs due to question company employees at separate hearings on Tuesday. It was not Fujitsu that relentlessly pursued thousands of local branch owner-operators, falsely accusing them of theft and fraud even after it became clear that the Horizon IT system was producing incorrect data. That was the Post Office. But the Japanese technology company built the ill-fated system, under a contract that has since been extended to run until 2025, reaching a lifetime value of £2.4bn. It also supported the Post Office in its pursuit of more than 900 post office operators, providing expert witnesses for private prosecutions of innocent branch owner-operators, many of whom were jailed. After the ITV dramatisation of the scandal brought it back into the headlines and helped prompt government moves to quash all related convictions, this week could be the first time that Fujitsu has been called to account in any meaningful way at the inquiry and a special hearing of the business select committee announced last week. Here’s what they might be asked. What did Fujitsu bosses know and when? MPs at Tuesday’s select committee hearing will interrogate what Fujitsu and the Post Office knew about flaws in the Horizon system and how early they knew it. The Post Office first became aware of Horizon’s deficiencies in 2010. However, the investigative journalist Nick Wallis, an expert on the scandal, has previously claimed that Fujitsu was aware of gremlins in the system before that. Fujitsu’s UK boss, Paul Patterson, is scheduled to give evidence to MPs, who will try to drill down into the timeline of corporate culpability. Patterson’s immediate predecessor, Duncan Tait, was handed a £2.6m payoff when he left the company in 2019, the Guardian revealed last week. MPs might ask about the terms of that payment. They could also seek clarity on whether it was Tait who made the now infamous comment, according to previous testimony by the former Post Office boss Paula Vennells, that Horizon was like “Fort Knox”, the US military base that is often conflated with the heavily guarded gold bullion depository nearby. Did Fujitsu contribute to wrongful prosecutions? At the judge-led inquiry, Fujitsu staff are due to give evidence about the company’s role in the various legal battles between the Post Office and victims of the Horizon scandal. Liam Byrne, one of the MPs on the business select committee, told the Guardian: “It’s high time Fujitsu broke their vow of silence about whether they put profit before people and stayed silent about Horizon’s problems when their evidence was being used to send innocent people to prison.” Four former Fujitsu employees who advised the Post Office on the Horizon system, including during prosecutions, will give evidence this week. MPs will be keen to quiz them on the role of Gareth Jenkins, the former chief architect at Fujitsu, who gave evidence defending the Horizon computer system in a number of the prosecutions. Should Fujitsu pay compensation? Calls have been growing for Fujitsu to contribute to compensation payments for Horizon victims, a bill that could reach £1bn, funded by taxpayers. This is likely to be one of the key targets for MPs on the select committee, particularly given that Fujitsu has yet to face any consequences, financial or contractual, for its flawed work for the Post Office. The justice secretary, Alex Chalk, has suggested Fujitsu could be forced to cough up if the inquiry finds it was at fault. MPs will question Patterson on whether Fujitsu expects any such claim from either the Post Office or the government and how it would react. “How much is Fujitsu going to pay towards the […] compensation now owed because their system malfunctioned so badly that innocent lives were destroyed,” said Byrne. Should Fujitsu be winning government contracts? Fujitsu has won nearly 200 public sector contracts worth £6.78bn, according to analysis by the procurement experts Tussell. As government officials began to realise the full horror of the Horizon scandal, they sought in vain to exclude Fujitsu from tendering for public contracts under the dubiously titled “Project Sushi”, the Financial Times reported on Monday. The Post Office also sought advice from a big consultancy firm in 2012 on how to extricate itself from the Horizon contract, a well-placed source told the Guardian. It didn’t work. The £2.4bn Horizon contract is still going and other contracts with government bodies including the Ministry of Defence and a £1bn deal with HM Revenue and Customs. The latter will come into sharp focus later this week because Fujitsu staff at HMRC are due to go on strike over pay. That could leave HMRC struggling for capacity, just at the peak time of year for tax returns being filed. Fujitsu and the Post Office have both repeatedly said that they would support the inquiry but were unable to comment while it was ongoing.