PEZINOK, SLOVAKIA (AFP) - A Slovak court on Thursday (Sept 3) acquitted a well-connected businessman of ordering the murder of an investigative journalist in a case that shocked the nation and exposed high-level political corruption, ultimately toppling the governing party.

Multi-millionaire Marian Kocner and two suspected accomplices - Tomas Szabo and Alena Zsuzsova - faced up to 25 years in prison for the double murder of Jan Kuciak and his fiancee Martina Kusnirova in February 2018.

"The crime was committed but it has not been proved that Marian Kocner and Alena Zsuzsova ordered the murder," Judge Ruzena Sabova said in her ruling.

"The court therefore acquits the defendants," she said, sentencing Kocner only to a €5,000 (S$8,065) fine for illegal weapons possession, as 60 bullets were found in his house.

The victims, both 27, were gunned down at home after Mr Kuciak wrote several stories on graft and the shady dealings of the high-powered entrepreneur who has ties to senior government politicians.

Prosecutors argued that Kocner ordered Mr Kuciak's murder in revenge for articles detailing his various property crimes.

They had called for Kocner and his alleged accomplices Szabo and Zsuzsova to be jailed for 25 years if convicted.

Mr Kuciak's father Jozef told journalists after the verdict that he was "left paralysed".

"We can only hope that justice will eventually prevail," he said.

Prime Minister Igor Matovic, elected on the back of an unprecedented wave of protests in the wake of the murders, said "it was obvious masterminds behind the murder want to get out of the clutches of justice".

"We believe that justice will wait for both of them," he said in a post on his official Facebook page.

President Zuzana Caputova, also elected on the back of the outrage, said she was shocked by the verdict, and that she expected it to be appealed in the Supreme Court.

The verdict is subject to appeal but it was unclear on Thursday whether one would be launched.

In his closing speech in July, Kocner denied murder.

"I am not a saint, but I am not a murderer either. I'm certainly not a fool who wouldn't realise what a journalist's murder would lead to," he told the jury.

In June, he had addressed Mr Kuciak's father in court saying: "I'm sorry about what happened to your son, believe me, but I have nothing to do with it."

Of the five suspects charged in the case, two have confessed their guilt and have already been sentenced.

Zoltan Andrusko, an intermediary in the murder plot, was sentenced to 15 years in jail in December 2019 after agreeing to a plea bargain.

Ex-soldier and contract killer Miroslav Marcek received a sentence of 23 years in April for gunning down the couple.

Prosecutors argued that Andrusko served as a go-between, hiring gunmen Marcek and his cousin Szabo at the request of his friend Zsuzsova, who was in turn following Kocner's orders.

The double murder plunged the country of 5.4 million people into crisis and triggered the largest demonstrations seen since the fall of communism.

Then Premier Robert Fico was forced to resign in March 2018 and was replaced by his populist left Smer-SD party deputy Peter Pellegrini.

But the opposition won this year's election, paving the way for a new centre-right government led by Mr Matovic from the ant-graft OLaNO party.

Former justice minister Daniel Lipsic, the murdered couple's legal representative in the trial, said Slovakia was apathetic before the double murder.

"The killings have roused Slovakia," Mr Lipsic told AFP.