BELLEVUE, Wash. - As investigators try to determine what caused a construction crane to collapse, killing a man, records show the crane's operator has a criminal history that includes six drug convictions, for cocaine and methamphetamine.

Investigators are examining whether operator error, structural failure or some combination of both caused the collapse Thursday that killed 31-year-old Microsoft lawyer, Matthew Ammon.

The state Department of Labor and Industries said the crane's operator, Warren Taylor Yeakey, 34 of Tacoma was being tested for drug use. The results have not yet been made public. He suffered minor injuries from the accident.

Yeakey told the fire department he was getting ready to shut down for the night when he heard a loud snap and the crane went down. He was able to pull himself out of the crane cage as firefighters used a ladder to retrieve him about 20 to 30 feet above the ground.

Yeakey's employer, Seattle-based Ness Cranes says it has a zero tolerance policy for drug use.

His brother-in-law told KING 5 Saturday that Yeakey's drug problems were long behind him.

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Another crane was brought in to remove the toppled one.

A large crane was brought in to the accident scene Saturday, to haul away the crane that smashed into the west side of the Pinnacle Bell Centre Apartments, killing Ammon, who lived on the top floor.

Ammon was a patent attorney for Microsoft. Friends and colleagues said he loved legal challenges, fast cars, football and playing cards, The Seattle Times reported Saturday.

He had only worked at Microsoft for five months, after moving from Kansas City. Ammon was originally from the Pittsburgh area, according to general counsel for Microsoft Brad Smith.

"He had an infectious personality, very warm person and brought a huge ammount of enthusiasm to everything he did," Smith said.

The 210-foot crane collapsed around 7:45 p.m. at the high-rise complex construction project on 108th Avenue NE near NE 4th Street, at 333 Bellevue Tower, which is an office building that has been vacant for a few years.

The crane also sliced through two other buildings, the Civica Office Commons and Plaza 305.

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Matthew Ammon worked at Microsoft.

108th Avenue NE between NE 2th Street and NE 4th Street will remain closed for at least a couple of days during the investigation. About 100 residents in the apartment building were also evacuated overnight. About a quarter of the building's occupants have been relocated to a nearby hotel.

Just trying to get this area back in shape will take months and the investigation into what caused it could take even longer. They will look at weather, mechanical malfunction, metal fatigue and again the operator is so important in all this because he not only operates it, it inspects it every day.

Meanwhile,  the state is now advising crane operators all over the state to carefully inspect their cranes for signs of problems as there is very little government oversight.

Businesses impacted

A number of businesses have been impacted by the crane collapse in the heart of Bellevue's financial district.

At is came down, the crane hit the Plaza 305 building and The Civica Commons building. According to the Civica Commons Building's Web site, some major companies are tenants in the building. They include Microsoft, Infosys Technologies, Metlife Financial Services and Morgan Stanley.

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The crane was still being dismantled Friday afternoon.

"Some of the offices are closed," said Richard Redecki, who works at Morgan Stanley.

"There's rubble, there's dust everywhere," according to Laurie Ascanio, who works in Liberty Financial Group, which is in the building's south tower.

Pacific Continental Bank was relocating its workers to other facilities in the Seattle area.

There are numerous construction projects under way in the area around the accident site. Work at many of those projects was halted.

Bellevue's mayor says he's relieved more people weren't killed in the accident

"If it occurred an hour earlier it would have been worse," said Bellevue mayor Grant Degginger. "If it happened during rush hour, it could have been worse."

The crane fell several feet from The Melting Pot restaurant, which was full of diners at the time. Everyone was evacuated and no one inside or outside the restaurant was hurt.

As officials continue their investigation, extra safety precautions are being taken at nearby construction projects. Iron workers at a construction site at the Bellevue Galleria were sent home Friday morning so engineers could assess the stability of their two cranes.

"It's a total safety issue. If this one's going to go down, we're that close, ours could probably go down too," said Jason Takahashi, iron worker. "We work with the crane. We're always below it, so it's a concern for us."