INDIANAPOLIS, Ind. - Police questioned at least three men Thursday in connection with the fatal shooting of an Indianapolis pastor's wife, reports CBS affiliate WTTV.

The three men were taken into custody Thursday morning after police served several search warrants at different locations across the city. Two of the men were arrested on unrelated parole violations, a police spokesperson confirmed.

The Indianapolis Star reports that in a previous high-profile case, the November 2014 slaying of 15-year-old Dominique Allen, the suspect was initially held in jail on a parole violation for 10 days before being charged in Allen's murder.

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Officers conducted DNA swabs on the three men to compare to evidence found at the crime scene.

Police say Blackburn was shot in the head during a home robbery, which detectives later linked to another nearby home break-in. Sources confirmed to the station that Blackburn was sexually assaulted in the attack.

No arrests have been made in the case. Just days after the killing, police quickly determined that her husband, Davey Blackburn, had no part in the killing.

Police haven't released many details about their investigation, although they did release surveillance images of a possible suspect. Detectives also recovered a handgun just blocks away from the murder scene. Authorities told the station that a credit card taken from Blackburn's home had been used at various locations in the city. Police said the transactions began the night Blackburn was shot.

Davey Blackburn remains confident the police department is doing all they can to catch his wife`s killer.

"They've assured us that they have the full breadth of resources at their availability. They've assured me that they've never seen this kind of a blank check that they've been given to be able to further the investigation," said Blackburn. "So we're really confident and hopeful that very soon, some of these promising leads that they have will turn into being able to find the person or the people who are responsible for this."