The father of a fallen Canadian soldier says "you're always looking over your shoulder" when you have a loved one serving in Afghanistan, and it would be easy to fall victim to a prankster calling to falsely inform you of their death.

Retired Col. Peter Dawe, whose son Capt. Matt Dawe was killed in 2007, made the comments after news this week that at least three relatives of soldiers serving in Afghanistan have been called and told falsely that their loved one had been killed.

No one has been arrested in connection to the prank calls, but Defence Minister Peter MacKay pledged Thursday that anyone charged would be "prosecuted to the full extent of the law."

Dawe told CTV's Canada AM most people who have loved ones serving overseas are already in a vulnerable state.

"When you have people deployed overseas you're always looking over your shoulder, you have to, you kind of expect the call or the notification," he said.

When Dawe's son was killed three people came to deliver the news -- someone he knew from his son's unit, the commander of the base, and a padre.

"It was a very strict protocol...and there's no nice way to provide such bad news, and he blurted it out, 'we lost Matt this morning,' and your world closes in on you," Dawe said.

Though most military people are aware that the Canadian Forces follows a strict procedure on notifications, a phone call with such bad news would still be incredibly upsetting, he said.

"You don't remember that the protocol is somebody in a black car that comes up and rings beforehand to make sure you're there and comes in and goes through the protocol. I don't think most people could break it down into that degree of rationality."

On Wednesday, MacKay called the prank calls "deplorable and despicable."

"To put those families through that stress is just disgusting in every stretch of the word," Mackay told reporters in Ottawa.

The relatives of at least three soldiers serving in Afghanistan have been called and told their loved one had been killed.

Although only one person has made an official complaint about the prank calls to officials at CFB Valcartier, the military have heard reports of three such calls received last week.

An official at CFB Valcartier says a prankster called one soldier's wife in the middle of the night and told her that her husband had been killed by a bomb on the battlefield.

The military is stressing that such information would never be delivered over the phone.

There are also reports that similar calls have been made in Alberta.

The calls are currently under investigation by the military.