Charles McGonigal, the former Special Agent In Charge of the New York FBI Counterintelligence Division, was allegedly turned in to the Bureau by his ex-lover, Allison Guerriero, after he ended their relationship and revealed he was not going to leave his wife for her.

During her time with McGonigal, Guerriero discovered a bag of cash in his Park Slope, Brooklyn apartment in October 2017, and when she questioned him about it, he claimed to have won the money through gambling on a baseball game.

Guerriero alleged their affair lasted over a year and that he would spend large amounts of cash on her and have sex in FBI-owned vehicles.

When the couple met, Guerriero was 44 and was a former substitute kindergarten teacher who volunteered for law-enforcement causes, working as a contractor for a security company while living at home with her dad. 

McGonigal, was 49 years old, had just started a new job at the FBI's New York office. 

The Southern District of New York unsealed a five-count indictment against McGonigal and Sergey Shestakov earlier this week, charging them with violating and conspiring to violate the International Emergency Economic Powers Act and with conspiring to commit money laundering. 

McGonigal, who retired in 2018, played a role in sensitive and high-profile investigations, including Robert Mueller's probe into Russia's purported ties to Donald Trump's 2016 presidential campaign. 

Charles McGonigal, now 54, walked free from Manhattan federal court on Monday on a $500,000 personal recognizance bond, following his arrest Saturday on charges laid out in two newly unsealed indictments.

One of the indictments, filed in Manhattan, accused McGonigal of violating US sanctions laws by working for Oleg Deripaska, a billionaire crony of Vladimir Putin, following his 2018 retirement from the FBI.

The other charges, filed in Washington DC, allege McGonigal took $225,000 in cash bribes from an unnamed former Albanian intelligence agent while leading the counterintelligence branch in the FBI's New York field office.

In an interview with Insider, Guerriero alleges that McGonigal used FBI resources for their relationship, including having sex in an FBI vehicle. 

She notes how McGonigal may have also abused his position of trust having once opened an FBI investigation into a U.S. citizen who lobbied for an opponent of the Albanian prime minister whom he had become close with.

Monday's indictment states that McGonigal was accompanied by the unnamed ex-spy when he secretly met with Albanian Prime Minister Edi Rama in September 2017, where he gave Rama 'FBI paraphernalia' and offered advice on lucrative oil drilling licenses. 

McGonigal is also accused of hiding from the FBI key details of a 2017 trip he took to Albania with the former Albanian intelligence official who is alleged to have given him at least $225,000 in three separate cash payments.

Once there, according to the Justice Department, McGonigal met with Albania´s prime minister and urged caution in awarding oil field drilling licenses in the country to Russian front companies. McGonigal's Albanian contacts had a financial interest in those decisions.

In an example of how McGonigal allegedly blurred personal gain with professional responsibilities, prosecutors in Washington say he 'caused' the FBI´s New York office to open a criminal lobbying investigation in which the former Albanian intelligence official was to serve as a confidential human source.

McGonigal did so, prosecutors allege, without revealing to the FBI or Justice Department his financial connections to the man.

In her interview, Guerriero claimed how McGonigal would spend lavishly on her - far more than his FBI salary would typically allow.

He would give her gifts of of $500 or $1,000 for her birthday and Christmas - and even gave a homeless person $100 on the street.

She only decided to blow the lid off their relationship after finding out he was married with two teenage children, and wanted to remain so, staying with the woman he would refer to as his 'ex-wife'.

After a drinking session and in a fit of jealousy, Guerriero emailed McGonigal's boss, William Sweeney who was in charge of the FBI's New York City bureau, directly.

She revealed details of the affair to him together with extensive dealings she had noticed McGonigal had with contacts in Albania. 

McGonigal had befriended Albania's prime minister had gone back and forth to the country several times. 

Indeed, McGonigal is now accused of spinning his own web of deception in multiple alleged schemes to profit from illegal foreign payments. 

The most stunning charge accuses him of working with a former Soviet diplomat-turned-Russian interpreter on behalf of Deripaska , a Russian billionaire they purportedly referred to in code as 'the big guy' and 'the client.'

McGonigal, who had supervised and participated in investigations of Russian oligarchs, including Deripaska, worked to have Deripaska's sanctions lifted in 2019 and took money from him in 2021 to investigate a rival oligarch, the Justice Department said.

Speaking of why she decided to blow the whistle on her former lover Guerriero claims: 'I was shocked, I was very much in love with him, and I was so hurt.' 

Three years after sending the email, federal agents showed up on her doorstep to inquire about McGonigal together with the allegations she had made over any Albanian connections he had made. They even showed her a picture of McGonigal with the Albanian Prime Minister.

The agents questioned her about all of her communications with McGonigal and focused especially on any 'payments or gifts' he may have given her. 

'Charlie McGonigal knew everybody in the national security and law-enforcement world,' Guerriero said to Insider. 'He fooled them all. So why should I feel bad that he was able to deceive me?' 

Guerriero has admitted that her grudge against him led her to carry out some obsessive and disturbing behavior herself, including writing to McGonigal's family. 

'I really did go overboard. I harassed them. I'm not going to deny that. I was horrible to them.' 

Things got so bad on Guerriero's end following the end of the affair that she spent a night in jail after she harassed McGonigal's wife, Pamela, and her children. 

It saw Guerriero breaching a restraining order that had been put in place against her in New Jersey following a series of 'nasty' emails and 20 telephone calls made to the wife and children in just one day alone.

'I am ashamed and embarrassed and sorry for my actions during the time that I was drinking,' she said to Insider.

Things also started to get worse for Guerriero when in early 2021, she was badly burned during a fire at her father's home leading her to ask for help through GoFundMe.

The FBI has refused to comment on any of Guerriero's tale but notes how the organization holds their employees to 'the highest standard' treating everyone equally, 'even when it is one of our own.' 

McGonigal worked for the FBI from 1996 until his retirement in 2018, and from 2016 until he left the bureau he was the special agent in charge of the FBI's Counterintelligence Division in the New York field office.

As well as playing a in high-profile investigations, including Robert Mueller's probe into Russia's purported ties to Donald Trump's 2016 presidential campaign, he also led an FBI team that investigated why CIA informants in China were being arrested and killed -- a probe that led to the arrest and conviction of Chinese double agent Jerry Chun Shing Lee. 

In a bureau-wide email Monday, FBI Director Christopher Wray said McGonigal's alleged conduct 'is entirely inconsistent with what I see from the men and women of the FBI who demonstrate every day through their actions that they're worthy of the public´s trust.'