SANTIAGO, Chile -- Cuban leader Raúl Castro landed in Chile on Friday to take center stage at a meeting of Latin American and European leaders but his visit will likely be overshadowed by Cuba’s human rights record and a controversy over whether his regime is harboring terrorists involved in a decades-old political assassination.

On Thursday, more than 50 representatives of the Independent Democratic Union (UDI), the largest and most conservative party in the Chilean government, demonstrated outside the Cuban embassy and attempted to deliver a letter of protest to the embassy, but its gates remained shut.

The UDI has a long-standing score to settle with the Castro regime. The organization accuses Cuba of harboring at least four Chileans charged in connection with the assassination of Jaime Guzmán, a founder of the party and its guiding light. Guzmán, a Chilean senator, was shot and killed on April 1, 1991, as he left Santiago’s Catholic University.

His murder shocked Chile and threatened to overturn its fragile democracy. The country had returned to civilian rule just a year earlier after 17 years of military dictatorship.

Two members of the extreme-left Manuel Rodríguez Patriotic Front (FPMR) were arrested, tried and sentenced to life in prison for their roles in Guzmán’s murder. But in 1996, they staged a daring jailbreak.

One of escapees, Mauricio Hernández Norambuena, turned up in Brazil six years later where he was arrested for his part in the kidnapping of a businessman. He remains in a Brazilian prison, despite efforts by the Chileans to extradite him. The UDI believes the other fugitive, Ricardo Palma Salamanca, might be in Cuba along with four other FPMR members involved in Guzmán’s murder. The party has repeatedly sought information about them but the Castro regime has ignored their requests.

The UDI has compiled a dossier of evidence against the suspects and passed it to Chile’s President Sebastián Piñera, who has promised to raise the issue with Castro during the CELAC-EU summit of Latin American and European Union leaders this weekend.

“We’re going to make every effort to talk to the Cuban authorities to ask for as much cooperation as possible to ensure that these people, who may have been involved [in Guzmán’s murder], are brought to justice,” Chilean Foreign Minister Alfredo Moreno told reporters.

Government spokeswoman Cecilia Pérez said Guzmán’s murder was an issue for the entire country, not just the UDI, while Melero said the Cuban embassy’s refusal to accept the party’s letter was indicative of the Castro regime’s disregard for freedom of expression.

“This is the lack of dialogue of the Cuban regime, that has once again refused to cooperate with the courts of law,” he said.

The Chilean Communist Party accused the UDI of political opportunism and double standards, saying it had done nothing to champion the human rights of Chileans persecuted by General Augusto Pinochet’s 1973-1990 military regime, which Guzmán supported.

Castro is not only attending the summit — he is due to assume the presidency at the end of the meeting. Observers both in Chile and Florida criticized the decision to make Castro the next president of CELAC and blasted Cuba’s human rights record.