Of the four keys belonging to the padlock that secured the bag in which Williams was found, one pair was found inside it with him. A second pair was found on a key ring in his apartment, Wilcox said.
There was no sign that evidence had been tampered with, such as traces of bleach. There was also no sign of a break-in or robbery in his neat, tidy apartment, she said.
She described his body as "peaceful" and said there was no indication of a struggle.
Wilcox also said there were no indications that Williams was feeling suicidal.
However, tests that might have revealed unusual or volatile poisons were ruled out by the decomposition of the body. Traces of alcohol and a chemical matching the party drug GHB were found, but both can occur naturally as part of the decomposition process, she said.
British media have reported that Williams' Internet history showed an interest in sex games and bondage, but Wilcox said the codebreaker had made only a handful of visits to bondage sites.
The coroner said there was no evidence of interest in claustrophilia, a fetish for enclosure in very confined spaces.
His apartment contained 20,000 pounds ($32,000) worth of high-fashion women's clothing, unworn and packed as purchased, Wilcox said, but she said she found no connection between his death and his interest in fashion and women's shoes and clothing.
There also was no indication that his death was connected to his work, she said.
He had not taken on any high-risk operations, and he worked only in the UK. There was no evidence of threats arising to him from his work, his employers testified.
Wilcox was highly critical of Williams' line manager, who did not report that he was missing for about a week after he died August 16. She said the inability of the manager to recall certain key bits of evidence concerning the week of Williams' death "is beginning to stretch the bounds of credibility."
When questioned, the manager said he assumed Williams was absent for a legitimate reason that he had forgotten about, even though he missed several meetings. They worked on a small team of four people.
The manager and other SIS employees testified from behind a screen and were identified only as SIS, plus a letter.
Williams was finally reported missing by a co-worker August 23, more than a week after the normally punctilious employee had last shown up at work.
"I can only speculate as to what effect this had on this investigation," Wilcox said.
The decomposition of Williams' body was hastened by the fact it was in a top floor apartment, where the temperature soared in the summer heat. The heating was mysteriously also turned on, despite it being a hot August, she said.
Police did not secure the scene until eight or nine days after Williams died.
Reports about the "body-in-a-bag spy" describe how two experts spent days trying to figure out whether Williams, who was athletic and of medium height, could have contorted himself in such as way as to lock himself into the North Face holdall bag, with a key to the padlock inside.
Video provided to the court shows one of them, Peter Faulding, folding himself laboriously into an identical bag placed in a bathtub.
Faulding, who specializes in rescuing people from confined spaces, told the inquest that he had tried to lock himself into the bag 300 times without success. A second expert witness, also of a size and build similar to Williams, tried 100 times to re-enact the feat without succeeding.
Neither ruled out definitively the possibility that Williams could have somehow done it alone. But a small trace of someone else's DNA was found on the bag, helping spawn all kinds of theories about who else might have been there.
Williams was recruited into the intelligence services straight from university, working with Government Communications Headquarters before MI6. The nature of his work and questions around why his spy agency bosses took so long to raise an alert about his absence have added to the intrigue surrounding his death.
Concerns about national security have been a factor in the 20-month delay in holding Williams' inquest, and an agency more used to working in the shadows has had an uncomfortably bright light shone into its practices.
A series of photographs provided by the Metropolitan Police show the tidy, impersonal interior of the spy's Pimlico home and the small white-tiled bathroom where his body was found.
A bicycle parked in the hallway is a clue to Williams' passion for cycling. A glimpse through a bedroom door shows a bed half-made, clothes lying on it. But little else can be gleaned from the images.