Huckabee, a folksy conservative who some think may take another run for the Republican presidential nomination in 2012, granted clemency to 37-year-old Maurice Clemmons nine years ago, The Hill reported.
Clemmons is the main suspect in the shooting of four Lakewood, Wash., police officers as they sat in a coffee shop Sunday.
In a statement released Sunday, Huckabee called the incident "a horrible and tragic event."
If Clemmons is responsible for the shootings, "it will be the result of a series of failures in the criminal justice system in both Arkansas and Washington state," the former governor said, adding Clemmons' release also was approved by the Arkansas parole board.
In 1990, a then-18-year-old Clemmons was convicted of burglary and theft of property and sentenced to 60 years in prison, the Washington publication reported. He was released after serving 11 years of his burglary sentence.
The Hill also reported Huckabee's former Wikipedia page was edited to include angry remarks about his award of clemency to Clemmons.
Huckabee, who has been criticized for his action, "will forever be known as the idiot who released the cop killer Maurice Clemmons. He was serving a 35-year sentence for armed robbery; the idiot released him after 9 years," an unidentified poster wrote.
The commentary has been removed from Huckabee's page and the notice, "Editing of this article by new or unregistered users is currently disabled," was posted. Any Internet user can edit or write Wikipedia entries.