They bored test holes in the playground and scooped vials of water from flooded basements. They burrowed through trash at the dump sites and prowled the streets in a big white "gamma-scanning van."
And in the end, after two months and a quarter-million dollars of investigation, specialists from the Environmental Protection Agency concluded that Friendly Hills is not another Love Canal.
In a jammed school gym in this suburban community at the foot of the picturesque Hogback Range southwest of Denver, federal officials today told relieved local residents that they have nothing to fear.
Fear and anger had been widespread among Friendly Hills' 4,000 residents since this summer, when a group of residents took an informal survey and concluded that children were dying of cancer at unnaturally high rates.
This group aligned itself with two large environmental groups, the Colorado Citizens Action Network and the National Campaign Against Toxic Hazards.
They charged that the neighborhood was beset with toxins. They demanded government help.
These complaints surfaced last fall when Congress was debating extension of the "Superfund," a large pot of federal money used to find and clean polluted areas.
As a result, stories about Friendly Hills were carried on the television networks and in several national publications, including The Washington Post.
These reports, however, led to an angry division in the community.
Some residents thanked the activists for raising questions.
Others damned them for spreading baseless fear -- and undermining property values.
Two local homeowners' associations condemned the group that had complained about toxic hazards. They refused to take part in an informal health survey of the neighborhood.
With neighbor squared off against neighbor, the people of Friendly Hills -- a staunchly Republican area where big government is criticized frequently -- turned to the government for help.
The local representative in Congess, Rep. Daniel Schaefer, a conservative Republican who boasts of his efforts to reduce the size of the federal bureaucracy, pleaded with EPA bureaucrats to do something.
Using Superfund money, the EPA launched a "multi-media environmental investigation."
At the same time, the state Health Department began a review of health statistics to determine whether Friendly Hills was sicker than other communities.
With a beaming Schaefer presiding, both agencies presented their findings at today's community meeting.
The conclusion: Friendly Hills is a clean and safe place to live -- no worse, and in some cases better, than the average community here in the Rocky Mountains.
"Of the more than 6,500 analyses conducted on samples," the EPA study said, "no exceedenses of criteria applicable to human health were observed.
"No environmental nor radiological anomalies capable of producing increased cancer rates were uncovered during our investigation."
Dr. Stanley Ferguson of the Colorado Health Department reported that cancer incidence in the community is in line with state and national rates.
The EPA study disclosed, as the concerned residents' group had suggested, that there were abandoned uranium mines in the area. That is not particularly unusual along the eastern edge of the Rockies.
But the report concluded that the mines are not adding dangerous levels of radioactivity to the area's land or water.
The EPA officials said more results are due on air-quality samples and plutonium tests, but they said they expect no serious problems.
Some residents remained skeptical. But most acted as if the government had handed them the perfect Christmas present.
"I hope," said John Miller, chairman of a Citizens Action Committee set up this fall to resolve differences among Friendly Hills' unfriendly factions, "that we can all forget our hostilities now and make this an even friendlier and safer place to live."