The security guard who's believed to have shot ex-convict Verne Sambury at the Persad's D Food King supermarket in New Grant, is now being questioned by police.
The security officer was taken into custody on Tuesday evening.
Sambury died at hospital on Tuesday afternoon from the wounds he suffered in the shooting.
The guard is an employee of Special Elite Investigations Service which has been providing security services to the supermarket for the past nine years.
CCTV footage of the shooting on Tuesday is also being reviewed by police in their investigations.