Lou Vincent's evidence in the Chris Cairns trial in London could leave him open to criminal charges under UK law.
Vincent spent five hours giving testimony as the first Crown witness before Cairns' lawyer began cross-examination on a dramatic day at Southwark Crown Court.
As he told the jury how he took 50,000 pounds to fix games in the United Kingdom, Vincent was reminded by the judge, Mr Justice Sweeney, that he had not beeng granted immunity from prosecution in return for giving evidence against Cairns.
Earlier, he told Vincent he was under no obligation to answer questions which might incriminate himself of crimes committed in the UK.
But Vincent continued to answer questions about other games he fixed, explaining that he was "desperate" for money and feared being blackmailed by bookies.
"They've always got one over you."
Cairns faces charges of perjury and perverting the course of justice. He is accused of lying under oath when he sued former Indian Premier League boss Lalit Modi for defamation. The case stemmed from a tweet by Modi saying Cairns had been sacked for match-fixing.
During his evidence, Vincent explained what he called the "art of underperforming" -- the ability to score 10 to 15 runs from around 20 balls, then get out.
But as the former professional cricketer explained that getting out is not as easy as it sounds.
The 36-year-old told the jury he fixed four matches while playing for the Chandigarh Lions in the rebel Indian Cricket League (ICL) on the instructions of Cairns, an allegation the latter has strenuously denied.
The first three went to plan, the fourth was a "disaster", according to Vincent.
"I can tell you exactly what happened, it feels like it happened yesterday," he told Crown prosecutor Sasha Wass, QC.
He was on 16 or 17 runs and about to face a left-arm spinner, when he decided to lose his wicket by getting stumped.
Vincent charged down the pitch, "but the ball did something funny" and he smashed it back over the bowler's head for six.
"My heart just raced, how did this happen?" Vincent told the jury.
He tried to miss the next ball in the hope of getting bowled, instead, he edged it and it raced to the boundary for four.
"I was supposed to get out, I've just hit 10 runs, this is a disaster," said Vincent, who ended up getting 28.
"It was a fix that went wrong, from my point of view."
Cairns was the next batsman in and he wasn't happy as they crossed paths.
"I could tell by the look on his face that he was fuming," Vincent told the court.
"I was anxious, I was worried about letting Chris down. I was under the instructions of Chris and I didn't deliver. And I didn't know what the consequences would be."
Vincent said he was summoned to Cairns' hotel room after the game and sat down on the edge of the bed.
"There was an angry look on [Cairns'] face, he picked up the bat, went to hold the bat above his head," said Vincent, motioning to the jury with his hands.
"I had clearly mucked up his fix for that day. It was a pretty harrowing experience really."
Cairns said the failed fix had "cost him millions" and accused Vincent of "going behind his back and working for someone else".
Vincent then asked the judge, Mr Justice Sweeney, if he could swear in court.
"[Cairns] told me to 'f*** off' because he doesn't want to see me again," said Vincent.
He left the hotel room devastated that he had destroyed his friendship with Cairns, whom he idolised.
Earlier, Vincent told the jury he accepted Cairns' approach to fix games because it gave him a "sense of belonging" during a time of depression.
"I felt like I'm part of the gang, I'm involved in something which is obviously out there ... I'm under Chris' wing and I'll never have to worry about money again."
Vincent alleged a number of players at the Chandigarh Lions were deliberately underperforming, including his former Black Caps team-mate Daryl Tuffey.
Tuffey has not been charged by UK police in connection to the case.
Vincent also described an ICL match against Mumbai, in which he said it became clear that both teams were trying to lose.
"This was a shambles ... it was embarrassing to be out in the field."
Mumbai batted first before Chandigarh struggled, deliberately according to Vincent, in the run chase.
"We had to act like we were disappointed," said Vincent.
That was until, the Chandigarh wicketkeeper came out and scored 41 runs off the final three overs of the game to win.
Vincent said there was an "uneasy" feeling among the players who knew the game was fixed, while the "the ones who weren't on the take were ecstatic and high-fiving each other."
After the match in April 2008, when Cairns allegedly threatened Vincent with a bat, Vincent moved to the United Kingdom with his wife, Eleanor.
After starting a T20 contract with county side Lancashire he alleged he got a phone call from Cairns.
Vincent told the court the pair met at a service station on the M1 motorway near Nottinghamshire, where Cairns was playing professionally, and bumped into international umpire Steve Davis.
They made small talk with Davis, who is also listed as a witness for this trial, before Cairns asked Vincent to underperform in his next match for Lancashire.
According to Vincent's evidence, Cairns said he no longer believed Vincent was working for anyone else but made it "clear that I needed to earn his trust back".
"He was friendly, inviting ... almost like that last game [in India] didn't exist. It made me feel great."
He told the court Cairns asked him to see if Lancashire teammate Mal Loye, with whom he had played for Auckland, would underperform too.
"Mal was taken back a bit. The conversation closed pretty quick," said Vincent.
Vincent went on to score 1 run off 5 balls for Lancashire. Afterwards, Vincent said, Chris Cairns and then-girlfriend Mel (now Cairns' wife) had dinner with Vincent and Eleanor.
Match-fixing was openly discussed by the quartet, said Vincent.
Eleanor Vincent was concerned about her husband's involvement, but Vincent said Cairns assured her "that everything was going to be okay".
Match-fixing made Vincent feel more confident, he told the court.
"From being depressed and lost in New Zealand, to having a professional contract in the UK with all the bells and whistles ... repairing my relationship with Cairns ... I started to feel good about the decisions I made. I was on a high."
And looking back, asked Ms Wass?
"Completely ashamed and embarrassed. Gutted."
Vincent said Cairns promised to pay him US$50,000 for each game in which he underperformed, but he only ever received US$2500, which Cairns gave him for spending money on a trip to Dubai.
Vincent said he was paid 50,000 pounds to fix games in the United Kingdom on behalf of others, including a bookie called Varun Gandhi.
He told the court Gandhi messaged him in 2009, at a time he was in a "dark space".
At this point, Vincent choked up and asked for a short break to gather his thoughts.
On his return, he explained that 2009 was a "horrendous year" for his mental health following his separation from Eleanor, financial difficulties and his reliance on alcohol and sleeping pills to cope.
And then the judge's reminder that Vincent did not have immunity from prosecution.
But Vincent continued, admitted to lying to officials from the English Cricket Board (ECB) when Loye and fellow player Murray Goodwin reported him for match-fixing.
He decided to come clean in August 2013, to Heath Mills, the head of the New Zealand Players Association.
"There was a major trigger. I was ashamed of who I was, I didn't like the man I saw in the mirror. I had led a double life. It was greed initially and then desperation.
"I met a wonderful woman whom I loved ... and she gave me the strength to do the right thing."
Vincent said Cairns asked him to write a statement saying the latter had never been involved in match-fixing. Cairns planned to use it in his defamation case against Lalit Modi.
"It would have been a complete lie," said Vincent, who declined to help.
Cairns' friend Andrew Fitch-Holland, a barrister by profession, then called Vincent on Skype in a conversation which Vincent recorded.
Ms Wass asked Vincent why he recorded it.
"It just didn't feel right. To be asked to back someone up in court with a lie, just didn't sit right with me," said Vincent.
"To then have the Skype call, I felt under pressure ... by recording the conversation, I knew something was going to be documented."
The Skype call was then played to the jury.
Vincent told the court he had confessed his involvement in match-fixing to English county cricketer Phil Hayes, Kiwi friend Stephen Pearson, former wife Eleanor, current wife Susie Vincent and fellow New Zealand cricketer Andre Adams, whom he unsuccessfully tried to get involved in fixing.
After giving evidence for the Crown for around five hours, Vincent was then subjected to cross-examination by Cairns' lawyer Orlando Pownall QC.
Mr Pownall suggested Vincent had come up with a "strategy" -- which included telling people what he had done, taking photos and recording conversations -- to present a favourable outcome on his "day of reckoning".
Mr Pownall said Vincent deleted files from his computer, including the manuscript of a book he was writing called Hero to Zero, and lied to the authorities before finally coming clean.
"Yeah, I was a disgraceful human being," said Vincent.
He invented a "pack of lies" in statements to the ECB and International Cricket Council (ICC) to "save his own skin", said Mr Pownall, not because of Vincent's mental state of health.
"Absolutely I lied," Vincent agreed.
Vincent also accepted he had committed a number of criminal offences in the UK.
"I understand that I've broken a number of laws in this country. And it's something I'm not proud of."
Mr Pownall also questioned Vincent about a July 2014 interview with Radio Sport broadcaster Tony Veitch, in which Vincent said he had "spent the last year trying to avoid going to jail".
That was a "slip-up", said Vincent, which he had "blurted out".
Mr Pownall responded: "Sometimes when someone blurts something out, they're telling the truth Mr Vincent."
Pownall: "It didn't cross your mind that you might end up in prison?"
Vincent: "No, not really. I accepted my mistakes and I hope what I'm doing will help other players, get out of that evil world."
Pownall: "And you hope that you won't go to jail?"
Vincent: "That doesn't come into my thought processes."
In giving evidence about his first ever match-fixing approach, from Varun Gandhi, Vincent told the Crown he was offered cash and a woman as a "present" in Gandhi's hotel room as part of a sponsorship deal.
He said he told Gandhi to leave the cash in the room's safe and then left.
But under cross-examination, Vincent admitted sleeping with the woman.
This was another lie, said Mr Pownall.
Vincent disagreed, saying it was an omission in his original statement to the ICC to protect his then-wife Eleanor from embarrassment.
"I did leave the room ... there was just a 10-minute [period]" before that happened, explained Vincent.
Mr Pownall is likely to continue cross-examining Vincent when the trial resumes tonight, New Zealand time.