BRATISLAVA, Slovakia (AP) — Thousands of people rallied in Bratislava and across Slovakia on Friday to mark the second anniversary of the slayings of an investigative reporter and his fiancee.

Jan Kuciak and Martina Kusnirova were shot dead in their home on Feb. 21, 2018.

The killings prompted major street protests unseen since the 1989 anti-communist Velvet Revolution in Czechoslovakia.

The ensuing political crisis led to the collapse of a coalition government headed by populist Prime Minister Robert Fico and the dismissal of the national police chief.

“As a society, we can never allow anything like that to happen again,” said Karolina Farska, an organizer of the anniversary events.

In a separate gathering Friday, 15 foreign ambassadors paid respect to Kuciak and Kusnirova in the capital.

“They died because Jan fought for truth,” U.S. ambassador to Bratislava Bridget Brink said. “More than ever we must protect press freedom and fight against corruption.”

Four defendants standing trial in the Kuciak case face potential prison sentences of 25 years to life. The man suspected of shooting the couple pleaded guilty. The other three, including the alleged mastermind, controversial businessman Marian Kocner, have all pleaded not guilty to murder charges.

Kocner had allegedly threatened the journalist following publication of a story about him.

Another suspect made an agreement to cooperate with prosecutors in exchange for a lower sentence. He received a 15-year prison term on Dec. 30.

Friday’s gatherings take place before a Feb. 29 parliamentary election in Slovakia.

Kuciak had been writing about alleged ties between the Italian mafia and people close to Fico when he was killed. The reporter also wrote about corruption scandals linked to the former prime minister’s leftist party.

Kocner had close contacts with some senior members of Fico’s party.

Kocner also allegedly hired a Slovak former intelligence official to carry out surveillance on Kuciak before his killing.