The highest court reversed the verdicts by the lower Criminal Court and the Appeals Court that found him not guilty of the charge.
In February 2013, former deputy prime minister Suthep Thaugsuban filed the libel lawsuit against Tarit for having suggested that Suthep had employed political influence regarding bidding for a government project to build 396 police stations all over the country.
Construction of the project has remained uncompleted until now.
Earlier this week, the defendant submitted his written confession and withdrew his testimony given at trial at the lower courts. Also, Tarit on Thursday had his lawyer place a Bt100,000 payment with the court intended as compensation for the plaintiff.
It was reported earlier that Tarit sought an out-of-court settlement with Suthep, 69, through mediation by a respected figure in legal circles.
The DSI ex-chief, 60, showed up at the Supreme Court on Chaeng Wattana Road early on Friday morning, over an hour before the court was scheduled to read its verdict at 9am.
The court rejected Tarit’s confession and withdrawal of testimony, explaining that those could not be done at this stage.
Regarding Tarit’s claim that he had reached an out-of-court settlement with Suthep, the court said no accord had been reached through negotiation, as the plaintiff did not want to compromise. The court ordered that the defendant’s Bt100,000 payment returned.
The top court then sentenced Tarit to a year’s imprisonment without suspension. After the verdict, he was accompanied by Corrections Department officials to Bangkok Remand Prison.
In his lawsuit, Suthep claimed that while serving as the DSI chief, Tarit had held press conferences between January 21 and February 4, 2013. Tarit told the media that the former deputy premier had instructed the Royal Thai Police, which was then under his supervision, to limit bidding to only one contractor for the entire country-wide project rather than allow bids for one contractor for each of the 10 regional police bureaux.
Suthep’s lawyer Sawat Charoenpol said on Friday that Tarit had sought an out-of-court settlement with the plaintiff, through mediation by many senior figures including former attorney general Kanit Nanakorn.
“But Suthep did not agree to a settlement because he had to consult with his legal team,” the lawyer said.