MILAN (Reuters) - A criminal investigation into accounting fraud inside British Telecom’s Italian unit has uncovered more evidence of what prosecutors say was the involvement of senior executives in artificially inflating the division’s financial performance.

British Telecom (BT)'s headquarters is seen in central London, Britain May 10, 2018. REUTERS/Hannah McKay

Here is a timeline of the unfolding scandal:

OCTOBER 27 2016: British Telecom says it wrote down the value of its Italian operations by 145 million pounds due to “inappropriate management behavior” at its Italian division but says the issue will not affect its full-year financial targets.

JANUARY 24 2017: BT CEO Gavin Patterson says in a statement an internal audit found “serious accounting irregularities” in its Italian operations that forced BT to write down the value of its Italian business by 530 million pounds and to cut estimated profits and revenues.

Patterson says BT’s integrity had been “undermined by the wrongdoing of a few individuals in one part of the business” and that London had been kept in the dark.

JANUARY 24 2017: Milan Prosecutors Office opens an investigation into alleged false accounting.

FEBRUARY 2017: Brian More O’Ferrall becomes chairman of BT Italy.

APRIL 2017: British Telecom files a complaint at Milan Prosecutors Office, saying it had fired Italy operations managers and employees it blamed for the irregularities. It argues BT was an “injured party” as it had payed additional taxes and more bonuses because of the inflated Italian budgets.

MAY 19 2017: Italian tax police search BT Italy headquarters, the Italian offices of nine suppliers to BT Italy, including IBM, and the houses of five former executives and employees of BT Italy that Milan Prosecutors formally put under investigation on allegations that they ran a conspiracy to fake transactions in order to inflate BT Italy’s financial performance.

JULY 28 2017: British Telecom pays 225 million pounds to its shareholders Deutsche Telecom and Orange to avoid a court battle over the accounting scandal in Italy.

JUNE 8 2018: BT CEO Gavin Patterson says he will step down amid shareholder pressure over lower revenues, a record regulatory fine and the Italian accounting scandal.

NOVEMBER 2018: Brian More O’Ferrall is replaced as chairman of BT Italy by Nicola Brenchley.

FEBRUARY 1 2019: Philip Jansen takes the helm as group Chief Executive Officer

FEBRUARY 13 2019: Milan Prosecutors Office officially close its investigation naming 23 suspects -- plus BT Italy itself as a company -- of false accounting and fake invoices, including for the first time three top executives of the group.