Gibbering sicko David Mazariegos smiled and laughed Thursday as prosecutors revealed he admitted to beating a beloved churchgoing Italian man to death for no reason – chillingly telling cops he took his innocent victim’s “spirit.”

The seemingly deranged 25-year-old menace was arraigned in Brooklyn Criminal Court on a first-degree murder charge for his alleged merciless attack on Nicola Tanzi, 64, near the Jay Street-MetroTech station Tuesday afternoon.

Senior Assistant District Attorney Sapna Kishnani outlined horrific new details about the savage beating — some of which came directly from Mazariegos’ broken tooth-filled mouth.

David Mazariegos, handcuffed and in a torn white garment, being escorted by two officers in front of a building.
Mazariegos was seen smiling while being escorted out of Manhattan court.Steven Hirsch
“Police interviewed the defendant and he confessed to beating the victim, robbing him, and ‘taking his spirit,’ as he put it,” Kishnani told the court.

Mazariegos allegedly punched Tanzi in the face at a security gate in Jay Street-MetroTech station, near where the security guard had worked for 15 years, the prosecutor said.

Mugshot of David Mazariegos.
According to Kishani, Mazariegos admitted to the ruthless murder.
“He then proceeded to stomp on the victim not once, not twice, but over and over and over again even while the victim’s body was totally limp,” Kishnani said. “The victim was completely unconscious and yet the defendant continued to stomp on his body.”

The senseless onslaught left Tanzi with a skull fracture, a crushed nasal bone and multiple other injuries to his face, the prosecutor said.

He died a few hours later.

A religious procession with a statue of a crowned figure in black and gold robes carried by men in suits.
Tanzi was 64 years old.facebook/john.l.heyer
Mazariegos allegedly then rummaged through Tanzi’s pockets, stealing debit and credit cards that he used to buy a samurai sword, Kishnani said.

Both the sword and credit cards were found on Mazariegos when police arrested him in Times Square, prosecutors said.

The harrowing details outlined by Kishnani also included the revelation that Mazariegos, of The Bronx, had a history of criminal cases being dismissed because of his mental health.

“Given the horrific nature of the case as I’ve just outlined it, the fact that this defendant is facing life without parole and the defendant’s history that I’ve just outlined we are asking for remand,” Kishnani said.

Black bag and a katana on the ground next to a person in dark pants.
Both the sword and credit cards were found on Mazariegos when police arrested him in Times Square.Chris Gonzalez @TheCritterfer
Mazariegos wore a tattered Tyvek suit during the hearing, which had even more holes than on Wednesday, when he flashed a sinister grin after a separate court hearing and disgustingly spat while being away carted by cops.

The deranged crook’s defense attorney didn’t ask for bail, but did request that Mazariegos receive medical attention.

Judge Philip Tisne remanded Mazariegos into custody without bail.