Maulama Akonjee, 55, who migrated to the United States from Bangladesh, and his assistant, 64-year-old Thara Uddin, were shot dead in broad daylight on Saturday afternoon in the Ozone Park neighborhood.
"An individual in custody for an unrelated incident has been questioned," a police spokesman told AFP. So far, no arrests have been made in connection with the murders, the spokesman said.
Police on Sunday released a sketch of a suspect , asking for public assistance in identifying the "adult male with a medium complexion, last seen wearing a dark colored shirt and blue shorts."
The sketch showed a man wearing glasses with a beard and moustache, and a high forehead with his hair combed back.
Funeral prayers are due to be held for Akonjee and Uddin on Monday afternoon.
Police say so far nothing indicates that the two men were targeted because of their faith, but members of the Muslim community have called the attack a hate crime.
They point to growing Islamophobia fueled by a series of terror attacks in the United States and abroad, as well as hostile statements by Republican presidential candidate Donald Trump .
The working-class area where the victims were killed, on the border between Queens and Brooklyn, is home to many Muslim families from Bangladesh.
Akonjee had been carrying more than $1,000, but the attacker did not take the money, police said.