In December, migrant bar workers Zaw Lin and Wai Phyo, both now 23, were sentenced to death after pleading guilty to the rape and murder of Hannah Witheridge, 23, and David Miller, 24.
The British couple’s battered bodies were discovered on the idyllic holiday island of Koh Tao in September 2014.
Several human rights groups questioned the verdict and warned that migrants had previously been falsely accused of crimes in Thailand.
On Sunday, Anonymous released a 37-minute video on social media accusing Thai police of poor policing and corruption. Days later, the network claimed responsibility for hacking 14 of the force’s websites.
Thai police have confirmed the attacks, but insist no confidential data has been taken.
Anonymous said it would support a boycott of Thailand until the country’s police forces change the way they handle criminal investigations involving foreign tourists.
“Anonymous has found that Thai police lie, fabricate evidence, do poor police investigating, contaminate crime scenes, loose DNA and evidence, accuse non-Thai nationals … [and] refuse to believe that their own Thai locals are responsible for any wrongdoing,” a masked member of the group said in the video shared on Facebook.
“We do not like the facts in this recent Koh Tao case and we do not believe the Thai court has convicted the actual murderers,” they added.
Officers investigating the murders have been accused of mishandling evidence and gross incompetence. However, Thai police have denied any wrongdoing.
A judge has also dismissed the allegations, saying there is no evidence to prove they mishandled the case.
“Even if the source of attack was from abroad, they will be convicted eventually,” they said. “It’s not a problem. Thai police are excellent.”
“They’re not good enough to hack into our system and steal any of our data,” they added.
Miller’s parents, who sat through much of the trail, said they are convinced of the migrant pair’s guilt.
In a statement, the family said: “David was an artist by temperament, so talented. He had a creative eye that he carried with him through life and in his degree. He was hard-working, bright and conscientious, with everything to look forward to.”
Reminiscing about Witheridge’s life, her family said: “Hannah was a beautiful, intelligent, loving young woman who poured joy into the lives of all who knew her. She was selfless and caring and made each and every day that little bit more wonderful.”