Originally Published: 22 MAY 22 14:08 ET

Updated: 23 MAY 22 13:56 ET

By Kiely Westhoff, Mark Morales, Laura Ly and Eric Levenson, CNN

(CNN) -- The New York City Police Department released two photos Monday of a suspect who is wanted for homicide in the unprovoked shooting on Sunday of a 48-year-old man on the subway.

"We need all eyes on this," police Commissioner Keechant Sewell said in a tweet. "(NYPD detectives) need your help identifying & locating this man who is wanted for homicide in the tragic, senseless shooting of a man on a "Q" train that was approaching the Canal/Centre St. station on Sunday."

In the images, the suspect is wearing a surgical mask, white shoes, gray sweatpants and a dark-colored, hooded sweatshirt. An NYPD official previously described the suspect as a "dark-skinned male who is heavyset with a beard."

The release of the photos came a day after Daniel Enriquez, a 48-year-old Goldman Sachs employee from Brooklyn, was fatally shot in the chest as he sat in the last car of the Manhattan-bound train traveling on the Manhattan Bridge, officials said.

The subway has been the setting for a series of disturbing crimes in recent months that have rattled the public's confidence in the safety of the transit system.

In January, 40-year-old Deloitte employee Michelle Alyssa Go was fatally pushed in front of an oncoming subway train. And last month, a man set off a smoke device and opened fire on an N line subway train in Brooklyn, injuring more than two dozen people. The suspect in that case, Frank James, fled the scene and was captured a day later after police released his name and image to the public.

Mayor Eric Adams, a former transit police and NYPD officer, has increased the number of officers on the subways and released a plan to address homelessness on the transit system. He has pushed for workers to repopulate offices largely left empty by the pandemic, and he acknowledged Monday that Enriquez's death hurts that effort.

"This is the type of employee I want to get back to work," Adams said. "Does this send a chilling impact on that? Yes."

Victim was shot without provocation, officials say

Witnesses to the shooting told NYPD investigators the suspect was walking back and forth in the same train car and "without provocation, pulled out a gun and fired it at Enriquez at close range as the train was crossing the Manhattan bridge," said NYPD Chief of Department Kenneth Corey.

The shooter and the victim had no interaction on the train before the shooting, and it appeared there was no dispute, a law enforcement official with knowledge of the investigation told CNN. While there were other people in the train car, Enriquez was the only person who was injured, said Corey.

When the doors opened at Canal Street, the shooter ran out of the subway car and out of the station and remains at large, the official said.

Officers responded at about 11:42 a.m. and found Enriquez with a gunshot wound to his torso. First responders rendered aid and transported him to Bellevue Hospital, where he died of his injuries, Corey said.

NYPD officers rode the Q train on patrol three different times before the shooting took place Sunday, the official said.

Enriquez had worked for investment bank Goldman Sachs for nearly a decade since joining its Global Investment Research division in 2013, the company said.

"Daniel Enriquez was a dedicated and beloved member of the Goldman Sachs family for nine years," Goldman Sachs Chairman and CEO David Solomon said in a statement. "He worked diligently to support our Macro Research team in New York and epitomized our culture of collaboration and excellence."

"We are devastated by this senseless tragedy and our deepest sympathies are with Dan's family at this difficult time."

Mayor Adams said the city is working to crack down on guns on the transit system, including by using technology -- "not metal detectors," he clarified -- to track guns on subways and by implementing checkpoints for buses.

"I use the subways a lot, I am in the system a lot, and it's unimaginable. You are sitting down going to brunch, going to visit a family member, a person walks up to you and shoots you for no reason," he said. "That is the worst nightmare and that is why I have been so dogmatic about one, getting illegal guns off the street, then getting the shooters."