Ed Mangini was the Senior Clerk at Family Court.
Among his duties was putting together the dockets for Judge Hilda Marsden. Judge Marsden was illegally receiving a commission for sentencing juvenile offenders to disproportionately long imprisonments at a private facility for sex offenders run by her cousin in Wellsburg, Ohio, and in turn, he was paid to fill her dockets with suitable offenders - even these secondary kickbabcks were large enough that Mangini, who earned $56,000 in his job as a court clerk, drove a brand-new Mercedes and owned a million-dollar beach condo in Florida.
After Judge Marsden sentenced Kim Garnet to a stay in Wellsburg instead of a New York facility - unilaterally convicting her on charges far more severe than the ones the DA's office had been willing to drop - Kim's attorney Miranda Pond and Detective Olivia Benson became suspicious and visited the Clerk's office to investigate Judge Marsden's records. When Mort, the Junior Clerk, offered to help them, Mangini quietly called Judge Marsden and informed her Pond and Benson were looking into her records. Mangini then overruled Mort's offer to help, until Pond and Benson were summoned to Judge Marsden's courtroom, where they were subsequently held in contempt.
Unfortunately for Mangini, once word of the incident reached Samantha Copeland, who had prosecuted Kim, she sensed a cover-up and looked up the records herself - and immediately realized why Marsden had gone to such extremes to conceal them: Kim was, at the very least, the 52nd teen she had sent to Wellsburg - not one of whom was initially charged with an actual sex offense. After deducing Mangini was working for Judge Marsden, he was brought in for questioning by Benson and Elliot Stabler. Though he initially requested a lawyer, he quickly reconsidered after being threatened with official corruption and tax evasion charges, then being reminded that, as it was the corrupt judge they were really after, all charges against him would be dropped if he helped put Marsden away.
Mangini confessed his entire arrangement with Judge Marsden and agreed to cooperate in an elaborate sting by the SVU and FBI against Judge Marsden in exchange for the charges to be dismissed, placing an additional case on Judge Marsden's docket: that of a 15-year-old (Garnet's friend Ethan Morse) who had taken his girlfriend for a drive in her father's car (which had been totaled as a result). He arranged a meeting in which the father, supposedly a childhood friend (actually an undercover Detective Stabler), who bribed her to increase the charges against the boy: she did just that in court the next morning and was promptly arrested for her crimes. (SVU: "Crush")