CANCUN, MEXICO; TORONTO -- One year after a vacationing middle-aged Canadian couple were found slain in a luxury Mexican Riviera hotel, their throats slashed ear to ear in a spectacular unsolved crime, Cancun investigators regard the couple's son, Anthony Ianiero, as a person of interest.

That does not mean an individual is a suspect, but rather, someone investigators would like to interview.
Were Domenic and Nancy Ianiero victims of a random robbery, as Anthony has long insisted?

Or, as some have speculated, were they slain by a professional assassin acting on orders?
Bello Melchor Rodriguez y Carrillo, Attorney-General for the state of Quintana Roo, was unequivocal.
The killers were contracted by Canadians, he said.

The Globe and Mail has spent months investigating the Ianiero homicides, in Mexico, the United States and Canada. In an exclusive, three-hour interview in Mr. Rodriguez's Cancun office, the prosecutor said he had not wanted to give the case file to Anthony's high-profile Toronto lawyer, Edward Greenspan, who ultimately secured a Mexican court order compelling Mr.

Rodriguez to disclose his findings.
For the past 10 months, Mr. Greenspan and Mr.

Ianiero have voiced certainty that the Feb. 20 killings at the Barcelo Maya Beach Resort stemmed from a brutal robbery. Mr.

Ianiero was in Canada when his parents -- Domenic, 59, and Nancy, 55 -- were slain, preparing to join them at the five-star resort for what was to have been his sister Lily's beach wedding. Still, he has said he knows for a fact that his parents had more money than the cash that was found on them.
Although it was a month before he spoke up, since then he has repeatedly said the prime suspect is a hotel security guard, Blas Delgado Fajardo, who befriended his parents before allegedly slaughtering and robbing them.

Not all of the Ianiero family shares that theory.
And on Thursday, four members of the Mexican investigative team provided a Power Point presentation to explain why they don't believe it either, revealing crime-scene photographs and detailing all the cash, items and travellers cheques that weren't taken from the room.
Along with Mr.

Rodriguez were Ludwig Vivas, state director of forensic services at the time of the killings, Raymundo Canche, director of the criminal investigation, and William Bastarrachera, Quintana Roo's chief of police.
They stressed they still view Mr. Delgado Fajardo as a person of interest, that he appears to have entered the United States illegally and that they are looking for him.

However, he is regarded as a peripheral rather than a central player in the deaths, Mr. Rodriguez said, one reason being that he was off duty on the night of the killings.
Nancy Ianiero was found in the hallway of room 4134, lying on her stomach, wearing her underwear and a white blouse but without a brassiere.

There was no evidence that either the front door, or sliding glass door, were forced open. Investigators believe she opened the door to someone she knew.
The hotel's computer shows that the last time a key was placed in the couple's door on the night of the homicides was about 11:10 p.

m. Witness interviews suggest that's when the Ianieros turned in for the night, causing investigators to discount the possibility the killers accessed the room with a different key and theorize that Nancy did, indeed, open the door.
York Regional Police - the Ianieros lived in Woodbridge, just north of Toronto - relayed a tip to Mexican authorities that someone known to Domenic Ianiero was a compulsive gambler who had incurred a debt of around $300,000, the investigative team said.

The Mexicans suggest that the Ianiero family have not been as co-operative as they would like. But Anthony Ianiero, a 36-year-old former hair stylist, said he hired Mr. Greenspan to get the answers the Mexican police weren't providing and to ensure a proper investigation.