Grisly details have been revealed about the slayings of an elderly couple in New Brunswick – at the same time that questions are being raised as to how their accused killer was able to get into the U.S. armed with a bloodstained chainsaw and various weapons.

Gregory Allen Despres, 22, is facing an extradition hearing in Boston so that he can be put on trial in New Brunswick. He has been charged with the murder of 74-year-old Fred Fulton and 70-year-old Veronica Decaire, who were killed April 23 at their home in Minto, 50 kilometres east of Fredricton.

According to documents filed in the U.S. Federal Court, which include a report from the RCMP on the homicides, an attacker gained entry to Fulton's home by cutting a screen door and kicking in a second door.

Gregory Despres (CP photo / WHDH-TV)

The investigators believe the person then went to a bedroom, where Decarie was stabbed several times.

The document suggests that Fulton got as far as his porch before the attacker dragged him back into the kitchen and cut off his head.

The RCMP report says Fulton's daughter made the horrific discovery three days later.

On April 25, a day before the bodies were discovered, Despres arrived at the U.S.-Canadian border at Calais, Maine, carrying a homemade sword, a hatchet, a knife, brass knuckles and a chainsaw stained with what appeared to be blood.

Although U.S. customs agents confiscated the weapons and fingerprinted Despres, the border guards decided that he should be allowed to enter the country.

Bill Anthony, a spokesman for U.S. Customs and Border Protection, said Despres, who was born in Canada, could not be detained because he is a naturalized U.S. citizen and he was not wanted on any criminal charges as far as customs officials could tell.

"Being bizarre is not a reason to keep somebody out of this country or lock them up," said Anthony, adding Despres had not violated any regulations.

Anthony admitted it "sounds stupid" that a man wielding what appeared to be a bloody chainsaw could not be detained. But he said, "Our people don't have a crime lab up there. They can't look at a chainsaw and decide if it's blood or rust or red paint."

On the same day Despres crossed the border, he was due in court in Fredericton to be sentenced on charges he assaulted and threatened to kill Fulton's son-in-law last August.

After clearing the border, Despres hitchhiked to southern Massachusetts, where a state trooper saw him wandering along the side of a highway. He was arrested after a routine check for outstanding warrants revealed that he hadn't shown up for the sentencing hearing.

A federal judge in Boston will decide on July 21 whether to send Despres back to New Brunswick to stand trial.