Detective Chief Superintendent Raymond Murray has said police will not apologise for arresting Mr McElhatton on suspicion of possession of Class A drugs only to "de-arrest" him hours later after the substance seized at his home was deemed innocent.
"No I'm not going to apologise but what I am going to do is explain and I think that is only but right," he said.
"Everything that happened in relation to that arrest and seizure is what we normally do."
Mr Murray said the officer who seized the item was justified in coming to the "reasonable suspicion" that it might have been drugs.
"It was white powder in an unmarked, unbranded clear plastic bag and around that are a number of individual tin foil pieces which are scrunched up and look like wraps, so the police officer seized that and reasonably suspects - and that is the threshold in law, because we are in the time and don't have the luxury of looking back - that these are drugs and makes a seizure."
He said the forensic lab subsequently came back to state that while the substance had not been identified it was not controlled drugs.
Mr Murray said the police conduct was "proper" throughout. He said police had not identified the suspect but acknowledged "people may have chosen to identify themselves".
"I know there is a lot of press speculation about blackening people's names," he said.
"Let me be very, very clear here today - that's not what we are about. What we are about is investigating the deaths of three children in a fast moving, high-intensity investigation.
"And actually the very fact that we moved so quickly for the forensic examination, the very fact that as soon as we got the results we expeditiously made it known to the individual and then we issued the update to the media, I think actually shows transparency."
Mr Murray said if police delayed sending out the initial media update on the seizure and arrest, officers would have been facing questions on why they were holding back information.
He added: "Police on the ground will never have that luxury of being able to work in hindsight, they have to work with what they reasonably and in good faith suspect at the time."