A former Post Office lawyer has apologised for prosecuting a sub-postmaster who was left homeless after being wrongly convicted of theft due to computer system flaws.
Lisa Brennan worked for the Post Office in Huyton, Merseyside, and was falsely accused of stealing £3,000 in 2003.
Giving evidence to the Post Office Horizon IT Inquiry Teresa Williamson said she was not told of the defects.
The prosecutor said she was sorry for "the harm" it caused Ms Brennan.
Ms Brennan was one of more than 700 Post Office branch managers between 2000 and 2014 handed criminal convictions after the system, installed and maintained by Fujitsu, made it appear as though money was missing.
The case has been described as "the most widespread miscarriage of justice in UK history".
Ms Brennan has told the inquiry being found guilty of theft was the "end" of her world, saying she had to sell her home, was left homeless with her daughter, and it led to the end of her marriage.
Ms Williamson said she was "angry" that material concerning the faulty computer system was not disclosed to her, adding: "We should have been told these things."
'Horrified and nauseous'
In December 2019, a High Court judge ruled that Horizon contained a number of "bugs, errors and defects" and there was a "material risk" that shortfalls in Post Office branch accounts were caused by the system.
Ms Williamson told the inquiry: "I'd like to take this opportunity to apologise to Lisa Brennan for being any part in the prosecution of her and for the harm it clearly has caused her.
"I'm really pleased that her conviction has been overturned and I hope she gets the compensation she deserves.
"But I really didn't know that the system was unreliable at the time that I had any part in her prosecution.
"But I'm still really sorry."
In her witness statement, Ms Williamson said that after reading a news article about issues with the Horizon system in 2009, she felt "shocked, horrified and physically nauseous".
"During my time working at the Post Office, I was never aware of any actual or potential bugs, errors, defects or other problems with Horizon," it said.
"My first knowledge of any issues with the system was when I read the Computer Weekly article in 2009 long after I had left my employment at Royal Mail legal services."
Offering her thoughts on her part in the scandal, Ms Williamson said: "I realise there was a lot of material that wasn't disclosed to me.
"There were things I should have known about but didn't know about.
"That makes me angry, and sad."
Asked why it made her angry, she said: "Because we should have been told these things.
"For example, I understand there were discussions at board level about the reliability of the Horizon system and that was not filtered down to the criminal law team."
Hundreds of victims in the scandal are awaiting compensation.
The inquiry continues.