To his friends, he was J.C. or J. Con, a three-sport athlete well known in the hallways of Patchogue-Medford High School.
He liked rap music and watching sports, played lacrosse, football and wrestling, and helped his father coach a youth recreational league and raise money for a local booster club.
Thursday, in a courtroom in Riverhead, Suffolk County prosecutors will paint a vastly different picture of Conroy. They say on Nov. 8, 2008, when Conroy was a 17-year old high school senior, he fatally stabbed an Ecuadorean immigrant, Marcelo Lucero, on a Patchogue street. The stabbing was the culmination of a night of attacks on random Latino victims, according to prosecutors, capping a year of similar attacks by Conroy and his friends.
Conroy will stand trial on charges related to Lucero's death and two other attacks that day, and one attack the preceding week.
In a statement to police, Conroy confessed to stabbing Lucero, saying he found the black folding knife used in the attack in a hotel room. Hours after the killing, Conroy asked how the case might affect the upcoming wrestling season, police said in pretrial testimony.
Of charges that Conroy targeted Latinos, his father balks, saying he never heard the term "beaner hopping" until District Attorney Thomas J. Spota said it in describing the term he said the teens used to describe their attacks on random Latinos. Conroy said his son - the third of six children - has friends, ex-girlfriends and even family members who are Latino.
"They know that what's been said out there absolutely is not true, that he's a racist," said Robert Conroy. "That's not Jeff. Anybody who ever got to know Jeff, they don't believe this happened."
Conroy's friends say they were shocked to hear of the charges, struggling to reconcile two starkly different images of the teenager they thought they knew. Many stand behind him, visiting him in Suffolk County jail in Riverhead, where he's been held without bail since the case began.
"He wasn't a racist kid, so there has to be more to it," said Vinny Garafola, 19, who graduated last year from Patchogue-Medford High.
For William Garcia, an Ecuadorean who graduated from Patchogue-Medford High last year, the struggle has been especially hard.
"He was one of my closest friends; he was always there when I had a problem or something," said Garcia.
Garcia, 18, said it was well-known at the high school that some students would go to Patchogue to randomly beat up Latinos. But Garcia said Conroy, as far as he knew, was not one to engage in that. "I don't really know what happened that night but I was really surprised about it," Garcia said. "Everything changes in a second."
For Robert Conroy, the trial will be an opportunity for his son to clear his name. He never misses a jail visit to see his son, never misses a phone call.
"I miss my son terribly," he said. "I'm anxious. I'm anxious to prove his innocence."