Slovakia's parliament on Thursday approved a constitutional amendment to reopen a probe into the 1995 kidnapping of the son of former liberal president Michal Kovac.
Hardline former prime minister Vladimir Meciar blocked the investigation into the crime in 1998 by introducing an amnesty for "crimes committed in connection with the kidnapping of Michal Kovac Jr", feeding suspicion he had arranged it to embarrass Kovac, his main political rival.
The amendment allowing the repeal of amnesties "that are contrary to the principles of democracy and the rule of law" was passed by 124 of the 146 lawmakers present in parliament.
The move opens the door for another vote planned by lawmakers next week to finally repeal Meciar's amnesty.
Several previous attempts to overturn it have failed.
The controversial Meciar, now 74, denied his administration's intelligence agency was behind the unsolved abduction during a rare TV appearance earlier this month.
Kidnapped in August 1995 by unknown assailants in neighbouring Austria, Michal Kovac junior was blindfolded and handcuffed, forced to drink a bottle of whisky and given electric shocks.
He came round in his car near a police station in the Austrian town of Hainburg, near the Slovak border and just 15 kilometres (nine miles) from Bratislava.
An Austrian court ruled in 1995 that it was most likely the work of Slovak authorities.
A movie titled "Abduction" based on the kidnapping that hit Slovak cinemas on March 2 has broken box office records, drawing 200,000 viewers in nearly a month.
A recent opinion poll showed that 63 percent of Slovaks said that even after two decades, they still want to see the kidnapping investigated.
Political analyst Grigorij Meseznikov told AFP that Thursday's move by parliament was dictated by "strong public pressure."
"The only acceptable scenario is to reopen the investigation into the abduction, this is what the Slovak public expects," Meseznikov added.
Meciar served as Slovakia's premier from 1990-91, 1992-94 and 1994-98. The United States and many European nations accused him of authoritarianism and corruption while in office.
Michal Kovac was the first president of independent Slovakia following the peaceful dissolution of Czechoslovakia in 1993.
During his 1993-98 term, the banker-turned-politician openly criticised Meciar's administration for attempting to curb newly won civil liberties after the collapse of communism in 1989.
In 1996, Kovac famously refused to sign Meciar's so-called anti-subversion law that would have curbed freedom of expression.
Kovac died of heart failure in October 2016.