The enquiry into the murder of prison officers Trevor Serrette and Nigel Jones continues, no one has been held for the crime to date.
Serrette, 48, was gunned down while sitting near his fruit stall in Sangre Grande on November.
Days later Jones was shot dead in full view of his four-year-old daughter while standing at the Old Siparia Road Junction.
Police in the Homicide Bureau of Investigations Region II on Tuesday said arrests were made last year, but those held were eventually released.
He said nine people were held in relation to Serrette's murder by divisional police, but did not have any further information.
The officer said a special team has been assembled to investigate which consisted of homicide detectives from regions I, II and III, as well as officials from the prison service.
Other senior police sources confirmed that no one has been held in relation to Jones' murder.