Thousands of Slovaks have been holding nationwide protest vigils in memory of a journalist and his fianceé, who were shot dead last Sunday.
Jan Kuciak, who was writing an article on corruption allegations, and Martina Kusnirova were killed at their home east of the capital Bratislava.
Marchers in 25 cities demanded an end to mafia influence, saying an attack on journalists was an attack on everyone.
Seven people have been arrested in connection with the killings.
Kuciak, 27, had been investigating suspected mafia links among Italian businessmen in Slovakia.
He was killed before he had finished the article, but it was published posthumously.
One of those arrested on Thursday was an Italian who had done business deals with officials close to Prime Minister Robert Fico.
Estimated crowd of 20,000 filled Bratislava’s Freedom Sq this eve, afterwards few thousand went to gov HQ, shaking the heavy iron gates and chanting ‘Enough of Fico’. Will it rattle him? We shall see. pic.twitter.com/cF4O6LtLCr— Rob Cameron (@BBCRobC) March 2, 2018
On Friday, marchers braved freezing temperatures in Bratislava carrying pictures of the dead couple along with a banner reading: "An attack on journalists is an attack on all of us."
President Andrej Kiska led the protesters, said to number between 10,000 and 20,000, in a minute's silence.
One demonstrator, Jozef Belovic, told Reuters: "There is a dirty mess all around here... and we common people have to put up with it."
Some of the protesters at the peaceful march then moved to the office of Prime Minister Fico to demand the government's resignation.
The pair were due to marry in May. The funeral for Martina Kusnirova was held on Friday. She was buried in her wedding gown in a ceremony attended by hundreds of mourners in the northern town of Gregorovce.
Kuciak's funeral will be held on Saturday in Stiavnik, close to the Czech border.
In his investigation, Kuciak alleged that Italian businessmen with ties to the feared Calabrian organised crime syndicate 'Ndrangheta had settled in eastern Slovakia, and spent years embezzling EU funds for this relatively poor region on the border with Ukraine
One of the men he named was Antonino Vadala, who was among those arrested on Thursday.
This is the first killing of a journalist in Slovakia's history.
Prime Minister Fico has offered a €1m ($1.2m; £890,000) reward for anyone who comes forward with information about the case.
He has also regularly attacked journalists in the past, calling them "dirty, anti-Slovak whores" and "slimy snakes".