Detectives investigating the murder of a company director said that they think his killer lay in wait for him to arrive at work.
It was also confirmed that 45-year-old Kingsley Monk and three other men were restrained with cable ties by their attacker, who detectives believe was armed and known to his victims.
Police said all four employees were assaulted, threatened with a handgun and had a mystery substance thrown over them during their ordeal, which lasted for several hours at the Driverline 247 unit in New Inn, near Pontypool, South Wales, on Monday. The unit was eventually set on fire with the men inside.
Businessman Allan Styles was able to rescue three men from the smoke-filled office early on Monday afternoon but he said father-of-two Mr Monk from Oakdale, South Wales, was already dead.
Mr Styles made the "gruesome" discovery when he noticed smoke billowing into his premises. He went next door to driver recruitment agency Driverline 247 and found Mr Monk tied up with three other men. Mr Styles managed to extinguish the fire and free the other men, but said there was nothing he could do for Mr Monk.
He said: "I was working and we saw the smoke. It was billowing in. One of them then came running into my place with his hands tied. I then ran into the unit next door. I could see the fire was really bad so I ran back into my place to get a fire extinguisher. Kingsley's body was on the landing so I stepped over that to extinguish the fire."
Although the blaze was quite big, it went out quickly.
He went on: "Kingsley was already dead. He was gone and tied up and God knows what. I don't want to say too much. I tried to resuscitate him but he had been dead too long.
"They (the three other men) had all been tied up. I had to cut the men free because they had been tied with cable ties and they were quite tight. One of the men was just in shock, jumping around, and one of the others was face down with his hands behind his back. There was blood everywhere."
Gwent Police, who are still investigating the motive for the attack, are continuing to question a 52-year-man on suspicion of murder, attempted murder and false imprisonment.