PIERS Morgan has admitted he was "unnerved" after realising he could have been STABBED by serial killer Bernard Giles who had a pen in his pocket during their interview.

The presenter's series Confessions of a Serial Killer returned tonight with killer Bernard who admits to murdering five female hitch-hikers in cold blood in 1973.

Eagle-eyed viewers spotted the potential weapon in the murderer's pocket as they said they were left "chilled" by how polite he was on the ITV show.

As he engaged with fans watching the show, Piers was asked: "How come Bernard was allowed a pen in his pocket? Surely he could stab and kill with it?"

He replied: "I only noticed it on him when we’d finished. Rather unnerving!"

But he explained that he was actually protected by armed guards off-camera who would have swooped if he had been put in any danger by Bernard.

Piers also went on to admit how he really felt about being so close to a man who was just 20 years old when he began his murderous rampage.

A viewer asked: "Is this the most terrified you’ve felt whilst interviewing a serial killer?"

He replied: "Yes. His demeanour was very scary" and later went on to tell Bernard he was "unsettled" by the interview.

Bernard was working as an electrician and did not have a criminal record when he carried out his harrowing crimes.

The killer - who is now 65 - avoided the death penalty by agreeing to confess to all five murders, but he will die in Brevard County high security prison in Florida.

Over a frenzied three-month period in the early 1970s, he embarked on a killing spree of unimaginable horror in Titusville, Florida.

His victims were all hitchhikers whom he picked up and drove at gunpoint to remote orange groves where he sexually abused and shot them.

They were Paula Hamric, a 22-year-old mother-of-two, Nancy Gerry, 18, Carolyn Bennett, 17, Sharon Wimer and Krista Melton, both just 14.

Viewers praised the documentary as "the best yet" from Piers as they were left chilled by the episode.

One said: "#ConfessionsOfASerialKiller really is the most chilling, un-nerving, compelling interview I’ve seen for some time. Remarkable insight into the ruthless, twisted mind of Bernard Giles."

Another added: "His glare his quietness and the fact he keeps constantly referring to @piersmorgan with yes sir #confessionsofaserialkiller is all so chilling and scary."

Someone else added: "This guys unbelievably calm, sitting there talking about killing people to Piers like he's waiting for a bus. #ConfessionsOfASerialKiller."

Another said: "This is the best one @piersmorgan has done. Very chilling emotionless guy. #ConfessionsOfASerialKiller."

Others couldn't believe how police Bernard was as he was quizzed on his killings - which he has never apologised for.

One said: " His normal polite manner was the most terrifying thing."

Another added: "Can’t handle the way this guy is so p***ing polite. It’s quite unnerving."