​No-0ne knows where accused D train killer Gerardo (Jerry) Sanchez spent his Friday, but it started badly.

According to the News, Sanchez, an exterminator, showed up a few minutes late for his job at Terminate Control on East 12th Street Friday morning and was sent home for the day. A friend saw him walking away, he assumed heading for the 4 train to go home to his room on Marion Avenue in the Bronx.

He may or may not have gotten there in between, but he was certainly headed that way, wearing a polo shirt that said "Terminate Control," on Saturday at 2 in the morning. He wasn't supposed to be on the D train - he generally switched from the 4 at Yankee Stadium - but there was a service outage on the 4.

From there it gets a bit confusing. According to the either dozen, two dozen, or nearly thirty other passengers in the car, Sanchez asked another passenger, Dwight Johnson, 36, to move his bags to free up a seat. Johnson refused, a decision the News calls "understandable" (the News went with both "a half-filled car" and a "nearly empty car").

Sanchez, who per the Post is either "hulking" or a slightly-built 5'6," argued with Johnson, at least six inches taller, until Johnson punched him in the face. At that point Sanchez pulled a steak knife and stabbed Johnson repeatedly in the hands and neck.

A passenger pulled the emergency cord and notified the conductor, who contacted police. He was told to seal the car, with a number of other passengers trapped inside, until police arrived at the Rockefeller Center station five minutes later. Sanchez managed to slip the knife out of the train door, but it was retrieved from the tracks later.

EMTs pronounced Johnson dead on the scene. Sources told the Post he appeared to be homeless.

Sanchez was charged with Murder 2 and weapons possession. Friends and neighbors told the News he's been acting strangely since he's been taking pain killers for an on-the-job injury. Sanchez has a prior arrest for dealing, and Johnson for weapons possession.