He said that investigators were speaking with witnesses and reviewing video from surveillance cameras.

The investigator looked up from his notes and spoke matter-of-factly.

Tonight's news conference was delayed for about an hour while investigators spoke with members of the victims' families.

Neighbors say the boy's older brother also lives in the apartment; it was not clear yesterday whether investigators had spoken with him.

Few details were available last night and the police said investigators had not spoken to the officers.

While it is possible to teach many investigative skills, every experienced and successful investigator speaks of instinct, which takes years to develop.

All police officials and investigators contacted yesterday spoke on the condition of anonymity, because they have not been authorized to talk about the case.

The unlicensed operatives are now subject to further investigation and investigators will be speaking to the security companies that deployed them.

The investigators, working for the Manhattan district attorney's office, spoke with one man in prison and one at his home.

But while 11 scientists and military staff officers have been questioned, Pakistani investigators have not spoken to the general.