On Tuesday, Brooklyn District Attorney Charles Hynes joined mourning family members of the eight-year-old boy who was killed in Borough Park last week and said the murder investigation will be thorough.

Hynes sat shiva with Leiby Kletzky's family at their Borough Park home and assured the mourners that justice will be served.

The grand jury is sifting through the evidence in the case.

"We are gathering with the police every piece of forensic evidence necessary to support our case," Hynes said. "This is a very, very careful process, you know. If you look at cases that have happened recently, if these kind of cases are rushed, mistakes are made."

The suspect, Levi Aron, is undergoing court-ordered psychiatric exams to decide if he is capable of standing trial.

Aron pleaded not guilty to kidnapping and murder charges.