George Zimmerman faced a lot of questions from the Sanford Police Department on several occasions about the night Trayvon Martin died.

Now the method one investigator used on Zimmerman is also being questioned.

The method is called assisted memory recall. We reviewed tapes of the interrogation with a former police detective, who has serious doubts about the questioning and the influence it may have had on Zimmerman's answers.

“Go ahead and make it up.  If it puts you back at the scene, it’s just, I mean, as far as what, as far as stuff you just recalled during that… it’s an old, old technique, and whatever, but…,” said Detective Christopher Serino with the Sanford Police Department.

The use of assisted memory recall, designed to help people remember the events at a crime scene by filling in the blanks between events with what may or may not have happened, is not widely used in investigations.

It was used by Serino and raises a red flag for private investigator James Copenhaver, who said it blurs the line between fact and fiction.

“Was Zimmerman telling the truth that time? Or, is he telling the truth now? Or is the entire story after that statement false and made up,” asked Copenhaver.

We asked the Sanford Police Department about their use of the technique, and received this e-mail response from Sgt. David Morgenstern:

“We will not be able to comment on your questions as it is a part of an active criminal investigation.”

Copenhaver said no one on his team would conduct an investigation like this.

“I can tell you that if any of my current investigators, being in the private sector, would have conducted an interview such as this, I would fire them,” Copenhaver said.

On Tuesday, Serino was voluntarily re-assigned to patrol duty.

Zimmerman’s attorney, Mark O’Mara, declined to comment at this time.