Video shows that a bicyclist pedaling through the searing heat on Saturday afternoon in Brooklyn did something real or imagined to anger a young man who drove past in an aging black Trailblazer.

The Trailblazer did a sudden U-turn at the corner of Pitkin Avenue and Pine Street just over the border from Queens. It then roared back and hit the bicyclist, who escaped catastrophic injury and managed to get the car’s license plate as it continued on its original path deeper into Brooklyn.

The bicyclist was doing more than he knew when he reported the incident. The report soon came to the attention of an old school first grade detective who was going through all summonses and traffic incidents in the immediate aftermath of the murder in broad daylight of an imam and his assistant Saturday as they walked from 79th Street onto Liberty Avenue at the edge of Queens.

After all, the Son of Sam had been caught thanks to a parking ticket his car got near the scene of his last attack.

The detective now saw that the bicycle incident had occurred 14 blocks away, and at the time it would have taken to drive that distance after a young gunman in a dark polo shirt and shorts stepped up behind 55-year-old Imam Alauddin Akonjee and 65-year-old Thara Uddin and shot each in the back of the head without saying a word.

Video from the shooting scene shows that the gunman had been following the imam and his assistant up 79th Street as they walked home from early afternoon prayers at the Al-Furqan Jame Mosque on Glenmore Avenue. The gunman had already been on the right side of the street in that video when his two targets crossed from the left side at mid-block. That made the detectives wonder if the gunman knew they would be turning right at the top of the block as part of their usual route.

Video also shows that as the two men crumpled fatally wounded onto the sidewalk, the gunman calmly turned around and strode hurriedly back down the block. Witnesses saw him with a gun in his hand. He left behind no shell casings, which suggested he had used a revolver.

The gunman was seen getting into a black Trailblazer and driving away. The direction and timing and description of both the driver and the vehicle—right down to the stickers in the windshield—were a perfect match with the man and the Trailblazer that made the vengeful U-turn to hit the bicyclist.

The license plate traced to 35-year-old Oscar Morel. His home address on Department of Motor Vehicles records was a half-dozen blocks further into Queens from the shooting scene, at a two-story building on Rockaway Boulevard.

Police put the building under surveillance, but the Trailblazer was not in the immediate vicinity. The vehicle was then spotted on the other side of the shooting scene, parked on Miller Avenue in Brooklyn. Cops noted that this man suspected of executing two men in plain view and then making a U-turn to hit a bicyclist had nonetheless thought to push in his street-side passing mirror so the trucks that trundle up the narrow block would not clip it.

Police put the Trailblazer under surveillance, and late Sunday they saw a man matching the suspect’s description emerge from a two-story house and approach the car. He then re-entered the house but re-emerged a short time later. He began to pull away when a police car zoomed up from behind. His Trailblazer struck a second unmarked car that cut off the intersection up ahead.

Homicide detectives took Morel to the 107th Precinct stationhouse. The video from the bicycle incident gave them all the evidence they needed to charge him right away with leaving the scene of an accident.

“A psycho,” remarked a senior cop who saw the U-turn video.

But the video from the shooting scene was not clear enough to make a definite identification. Morel reportedly did admit to being in the neighborhood. He then asked for a lawyer.

After the Queens district attorney’s office secured a search warrant, detectives went through the house on Miller Avenue and found a revolver they believe to be the murder weapon. They also found clothing matching that of the gunman.

The detectives were certain they now knew who had gunned down the imam and his assistant. That left another big and disturbing question.

Why?

Many of the mourners who assembled in a municipal parking lot near the mosque for a memorial service on Monday afternoon seemed certain that the killings had been a hate crime. They held up signs saying “We Want Justice” and “We Are Muslim Not Terrorist” and “We Are Muslim We Want Peace.” They spoke of the imam as seemingly everybody did; a man of piety and peace, exactly the sort of leader we all now need.

Several speakers made reference to politicians who trade in bigotry and xenophobia, but nobody mentioned Donald Trump by name, even though he was that very afternoon giving a big speech about using “extreme vetting” to fight Islamic terrorism.

After the talking was done, two plain wood coffins—the imam’s covered with a green patterned cloth, the assistant’s with a brown one—were removed from a pair of black hearses. One of the imam’s seven children, 25-year-old Saif Akonjee, stood by his father’s remains wearing a black turban and began the prayer.

“Allah…”

He paused and there was a hush. The subway rumbled underfoot. A plane overhead descended toward nearby JFK Airport, where a false report of shots fired had caused a panic the night before.

“Allah…” the son intoned again.

There came another hush, more complete, peace such as the imam sought to bring in his native Bangladesh and during his four years in America, first in the Bronx, then here in Queens.

He had given his last sermon on Friday and he had called in his native Bengali for the faithful to challenge bigotry with the power of peace. The very sound of his voice seemed to carry the same message at the early afternoon prayers on Saturday, which concluded just minutes before the murders.

“Such a beautiful voice,” a worshipper later said as the imam’s slippers and those of his assistant still lay by the two large bloodstains on the sidewalk.

The imam’s voice was now forever silenced. But the message remained after the hearses bore the two coffins away and a crowd of mourners marched past the murder scene, again calling for justice.

On Monday night, Morel was charged with the two killings. He was expected to be walked from the 107th Precinct after 10 p.m. We are left with the imam’s message and the question of why anybody would ever want to hurt a peacemaker such as we all need.

Maybe it was in fact a hate crime, even though Morel has not as of yet been charged with one. Maybe it was a homicidal version of the psycho U-turn that allegedly followed it. Maybe it was a bit of both hate and craziness, punctuated by calmly pushing in the passing mirror lest something happen to it.

“We may never know,” a senior police official said.

Editor’s note: This story updated to reflect suspect’s age. Tuesday, Aug. 16, 8:00 a.m. ET