Police investigating the attempted murder of Detective Chief Inspector John Caldwell have released a 47-year-old man following questioning.
Detective Chief Inspector John Caldwell was shot several times at a sports complex near Omagh in Co Tyrone on 23 February.
A 71-year-old man, arrested in connection with the investigation, was released earlier this week.
Two other men, aged 33 and 57, were previously arrested under the Terrorism Act, and taken to Musgrave Serious Crime Suite for questioning, remain in police custody at this time.
The PSNI's Major Investigation Team continues to ask for the public's help and is appealing for witnesses or those with information to get in touch.
Detectives are also highlighting a reward of up to £20,000 from Crimestoppers, who are a charity and independent of the police.
The reward is offered for information given directly to Crimestoppers that leads to the arrest and conviction of those responsible for the attempted murder.
The PSNI has released CCTV imagery of the car used by the gunmen.
The blue Ford Fiesta, registration number MGZ 6242, had been fitted with false plates, FRZ 8414, prior to the attack.
The car was later found abandoned and burnt-out on the Racolpa Road.
