There would be no logical reason to arraign the only witness to the crimes with the other defendants, especially if the defendants were being charged with violent offenses and had alleged murdered another one of their criminal cohort.
Police determined that the second family of victims named "Khan" were Indian because the family home had statues of Hindu gods.
Khan is a common name for Muslims in SE Asia, including India. A Muslim household would not display Hindu gods.
Chesley Watkins, the episode's antagonist seems to have committed a number of benefits related frauds which would have allowed her to be held in custody while awaiting trial for them. There was no reason that the murder cases would have to had to be premised upon the testimony of a single witness, thus allowing her to possibly be freed if something happened to that witness.
The front door of the house of the first victim family is seen to be hinged at the left (when the mother opens it from the inside) and then later in long-shot, when the door is opened by the Realtor: is seen to be hinged at the right.
A great deal is made of the fact that the assailants use machetes in the commission of their crimes as if machetes were common items and not difficult to track. Assuming that the machetes were being purchased within 100 miles of New York City and were all the same brand, it wouldn't be difficult to locate stores which recorded multiple or unusual sales.
It would be far easier if the machetes were sold inside of the city because machetes would not be commonly sold items in an urban area such as New York City.