Former CI╔ chief executive the late Mr Michael McDonnell was "shafted" and "driven to distraction" by plotting and scheming at the company, Mr Michael Lowry told the rail signalling inquiry yesterday.
Mr McDonnell, who retired from his post in February this year, was due to give evidence to the inquiry but he died in tragic circumstances in April.
His widow recently delayed but failed to prevent the inquiry from continuing its hearings on the grounds that her late husband's good name was in jeopardy from the evidence of witnesses he could not refute.
Mr Lowry, former minister for transport, energy and communications, told the inquiry he knew Mr McDonnell as a very decent, honourable and efficient public servant who put protection of the public purse as his number one priority.
At CI╔, however, his efforts were thwarted by cliques of people who resisted change and manoeuvred to keep all the senior posts in the company for themselves.
"He (Mr McDonnell) was undermined deliberately, he was shafted in the company and he was driven to distraction," said Mr Lowry.
Mr Lowry was testifying on the final day of direct evidence to the inquiry before cross-examination of witnesses begins next Monday.
He told the inquiry that officials in his Department repeatedly expressed concern about the management structure of CI╔ during his time as minister between December 1994 and November 1996.
The company had no chief executive when he took over the Department.
In 1995, the company finally agreed to appeals to bring in fresh blood and advertised a range of senior positions, including that of chief executive and Mr McDonnell was appointed in May that year.
Mr Lowry was unable to shed light on the troubled mini-CTC rail signalling project or the CI╔-Esat deal initiated during Mr McDonnell's time at the helm.
The signalling project was only at planning stage when Mr Lowry was forced to resign in November 1996 and CI╔ did not begin discussions on a deal with Esat until the following January.
Mr Lowry granted then Esat boss Mr Denis O'Brien the first independent mobile phone licence in October 1995, but said he had no knowledge of Mr O'Brien's interest in laying landline cables along CI╔'s railway lines at that time.
Mr Lowry's successor, Mr Alan Dukes, told the inquiry he did not know of Mr O'Brien's plans until May 1997, when Mr O'Brien mentioned it to him in an "offhand" manner as an idea he had.
Mr Dukes said he was greatly surprised to hear just a few weeks later, between the general election and the formation of a new government, that Mr O'Brien had signed a deal with CI╔.