A teenaged girl was also shot in the neck and a baby was found unscathed inside the vehicle where the three bodies were discovered, according to Arapahoe County undersheriff Mark Campbell.
Davidson was on the run after escaping from a federal prison camp on Sunday having served just five weeks of a 21-month sentence.
The Colorado 'spam king' was convicted of sending millions of spam messages promoting penny stocks which he then traded when the price rose. Police estimate that he made more than US$3m before he was caught.
Davidson specialised in making his messages appear as though they had come from legitimate origins by changing the header information and then spamming hundreds of thousands of addresses.
Following his conviction for tax evasion and falsifying email headers Davidson was fined US$714,139 and had gold coins and property seized by the authorities.
"What a nightmare, and such a coward," said US Attorney Troy Eid in an emailed statement. "Davidson imposed the 'death penalty' on family members for his own crime."
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iTnews State of Security Breakfast Sydney
iTnews Executive Retreat - Security Leaders Edition - VIC
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