Detective Johnny Corso brings in this guy, another "resident" by the name of "Marco" who is less than forthcoming with any information about the suspect - that is, until Mike Haines tells Corso to check him out. Fearful that the cops might search his pad, "Marco" describes the guy who was with the suspect.
"Marco" was played by Sam Waterston, and the reason I put his name in quotation marks is because I want to make the argument that he was actually Jack McCoy, the character Waterston played on 'Law & Order' for sixteen years. Jack McCoy grew up in Chicago, the son of an abusive, bigoted cop who would beat him and his mother for failing in his eyes. (The father would later die of cancer.) Since he would write an article for the New York University Law Review in 1972 (in defense of Catholic priests who protested the Vietnam war), two years after he began work as a prosecutor, it could be that he chose that publication because he himself was an alumnus of their school of law.
One reason why he may have gone to NYU's School of Law was to put distance between him and his father.
Since he started working as an ADA in 1970 (according to the 'L&O' episode "Second Opinion", which introduced him), McCoy would have been in law school by November of 1967, which is when the 'N.Y.P.D.' episode "Murder For Infinity" took place. (I'm not saying he went directly to work for the D.A.'s office upon graduating, but it does take three years to complete law school in the United States.)
And that flophouse down on 7th Street would be walking distance to the school. Maybe it was a dump, but Jack probably didn't have access to much money at the time. Even later in life, when he was making a very nice living as the Executive ADA for New York City, he was appreciative of a bargain. ("$362 a month for a 3 bedroom apartment? I'd kill for it.")
Since he wasn't really into that scene, I doubt young Jack McCoy was a drug user, not even the recreational stuff like marijuana. No, as often hinted at in 'Law & Order', alchohol was Jack's personal drug. So I don't think he panicked about the cops searching his pad and finding any narcotics. I think he had something else to hide in there - I'm thinking it was an underage girl. Whether she was still in high school or an NYU undergraduate freshman, she could also have been the girl who would later become the first of Jack's wives. (He was married twice.)
As for the name of "Marco".....
As everyone knows from the movie "National Lampoon's Animal House" (which counts as a reference for Toobworld since it spawned a TV spin-off, 'Delta House'), college students come up with odd nicknames for each other. Sometimes they're based on the student's name - like "Bluto" Blutarsky". Others have something to do with their looks or their personalities. (If you ever want to know why Larry Kroeger got the frat name "Pinto", you better read the original story. I'm trying to run a clean blog here! Or write to me privately.) And sometimes there's no real splainin to be found - just ask my friend Zoilo. (Actually, there is a story to that one, but it never made sense, even to a nonsensical guy like me, why he got saddled with it.)
Perhaps Jack McCoy ended up being called "Marco" by his college friends as a corruption of his last name. He may have later been a fan of the punk scene and the band The Clash, but back in the sixties, who wasn't into the Beatles? Maybe as a tip of the hat to Paul McCartney, his friends first started calling him "Macca", but eventually it devolved into "Marco".
Several decades after the incident at the flophouse, there would be an investigation into a crane collapse at a construction site. The company that was in charge of that site was owned by Wayne Hardy, who probably looked very similar to Detective John Corso in his youth. But Jack McCoy never would have seen a resemblance when he saw Hardy interviewed on the news. After all, his encounter with Detective Corso probably lasted no more than twenty minutes and it happened more than forty years earlier. And in his later years, Hardy no longer looked like the younger Corso.....
So that's my argument for the character of Marco, in just one scene from 'N.Y.P.D.', being Jack McCoy, with the second-longest tenure on 'Law & Order'.
Maybe. I'm not married to the idea.
But just so's ya know, I'm not doing this to buttress the defense of Jack McCoy's inclusion into the TV Crossover Hall of Fame. He was rightfully inducted in December of 2006 based not only on his 368 episodes of 'Law & Order' but also his three episodes of 'Law & Order: Special Victims Unit', two episodes of 'Law & Order: Trial By Jury', two episodes of 'Homicide: Life On The Street', and the TV movie "Exiled".
This is just gravy.
"Some of us were wondering how long it'd take
the real Jack McCoy to rear his shaggy, hippy, liberal head."
ADA Josh Latham
'Law & Order'