A retired NYPD detective whose investigative tactics have come under scrutiny as part of a review into old convictions in Brooklyn was confronted in court Wednesday by two men who were jailed in part due to his testimony.

The dramatic clash happened outside a courtroom in downtown Brooklyn, where Lou Scarcella was being questioned as part of a hearing for Rosean Hargrave, a prisoner of more than 20 years who's seeking to be exonerated in a corrections officer's murder in Crown Heights in 1991.

As Scarcella left court, he walked past two men who had been investigated by Scarcella decades ago. The men, Kevin Smith and Derrick Hamilton, each served more than 20 years in prison before they were released on parole. They're currently seeking to have their convictions overturned. 

"Scarcella, why did you do it, man?" Smith and Hamilton shouted after the retired detective. "Why you do it? You framed us! You should go to jail for your actions!"

Scarcella continued to walk, saying nothing. 

Hargrave's family, who were also in the hallway, recognized Smith and Hamilton. Hargrave's mother sobbed, and overcome by emotion, was rushed to the hospital.

"He put my son in jail for 23 years for something he didn't do," Hargrave's mother cried to Smith and Hamilton as they embraced her. 

Smith, who served 27 years before his release, and Hamilton, who served his 21 years, said they came to see Scarcella and to support Hargrave's family.

"I'm happy his mother is alive," said Smith. "Mine is dead. I came to consult them because I wanted to console them. It hurts to see a mom, sister and family suffer for something the man might not have done."

"I'm just hoping the justice system do what's fit and overturn his conviction," he said. 

When Hargrave's attorney Pierre Sussman questioned Scarcella on the stand, Scarcella, who had two personal attorneys by his side, said he didn't remember ever arresting Hargrave and denied being the lead investigator in the case.

He was polite, often smiled and frequently said he had no recollection of events.

Asked whether he responded to the crime scene in the case, for example, Scarcella said, "I don't remember. It was 22 years ago."

Hargrave's sister told NBC 4 New York of seeing Scarcella on the stand, "To see this man and he don't remember nothing now. This man don't remember nothing. My brother's been sitting in jail for 23 years."

When prosecutors had a chance to cross-examine Scarcella on the stand Tuesday, they declined, saying they had no further questions.

Since taking office in January, Brooklyn District Attorney Kenneth Thompson has intensified the work of the review unit, agreeing to re-examine 90 cases from the 1980s and 1990s to determine if there were wrongful convictions. Most of them stem from concerns about Scarcella's investigative tactics.

Scarcella has been accused of fabricating confessions, manipulating witnesses and intimidating suspects in other cases, charges he denies.

Of 57 Scarcella-related cases, the review board has determined that 11 convictions should stand, prosecutors said. 

Follow Marc Santia on Twitter @MarcSantia4NY