The maniac accused of viciously stabbing two strangers – including a good Samaritan – during a rush-hour attack at Grand Central this week told investigators he lashed out because one of the victims stepped on his shoes, prosecutors said. 

Gavin Ferguson, 30, was arraigned at Manhattan Criminal Court Thursday night on a top charge of attempted murder in connection to the 7:20 a.m. Wednesday attack on two men, 28 and 32, on board a southbound No. 5 train.

Assistant District Attorney Grace Snider revealed in court that Ferguson initially denied he was even at the scene of the brutal knifings – but then admitted to cops he committed the violent act because he viewed the shoe-stepping as an act of disrespect.

Ferguson was walking toward the open exit doors when he whipped around and slugged a 28-year-old man who stepped aside to let him off the train, according to a criminal complaint that cited video of the wild scene. 

That sparked a brawl between the two men that escalated when Ferguson allegedly used a distinctive knife with a pink and purple handle to stab him in the stomach, cops and prosecutors said. 

When a 32-year-old man intervened in the melee – allowing the first victim to escape – he became Ferguson’s new target and got knifed in the stomach and buttocks, the court papers recounted. 

That victim even jumped onto the bench of the train car to dodge his attacker’s blows, according to the prosecutor. 

Both victims were taken to Bellevue Hospital, where they were listed in stable condition.

Ferguson, of the Bronx, ran off, but was picked up by cops several hours later at his workplace, where he was still toting the distinctive knife – but had trashed the clothes he wore at the time of the stabbings, Snider said.

Investigators had pin-pointed Ferguson as a suspect since he dropped his phone at the scene of the attack – and then called it, asking for the device to be returned, according to the ADA.

Snider described the attacks on both victims as unprovoked.

However, Ferguson’s attorney, Paul D’Emilia, told The Post his client – a full-time plumber and U.S. citizen who has been in the U.S. since he was 15 years old – did not start the subway clash. 

“While he was commuting to work on the subway he was jostled and spit upon by one of the individuals on that subway car,” D’Emilia said in a statement. “When Mr. Ferguson attempted to exit the car, he was punched repeatedly by that same individual as well as the second individual.”

Then Ferguson had no choice but to defend himself and escape the “repeated blows,” his lawyer argued. 

He added that this case is Ferguson’s first brush with the law and he has multiple family members in the city. 

“We are confident that when details of the assault on Mr. Ferguson are presented to the District Attorney he will be exonerated,” D’Emilia said. 

In addition to the attempted murder rap, Ferguson was also arraigned on assault and attempted assault charges. 

He was ordered held on $500,000 cash bail or $750,000 bond by Judge Louis L. Nock, over prosecutors’ request for him to be locked up without bail.

He is due back in court on Monday and could face between 5 and 25 years behind bars if convicted.