At the time of the massacre, on July 31, 1991, the Medininkai border crossing point lay at the border of the Soviet Union. Lithuania declared independence on March 11, 1990.
The still unknown assailants brutally murdered Antanas Musteikis and Stanislovas Orlavicius, volunteer Lithuanian customs officials; Algimantas Juozakas and Mindaugas Balavakas, Lithuanian rapid reaction force police officers; and Juozas Janonis and Algirdas Kazlauskas, traffic police officers. They were shot in the back of the head.
Ricardas Rabavicius, another police officer, died in hospital after several days.
The sole survivor was Tomas Sernas, then a customs officer. Sernas recently became a priest.
Investigators believe the killers are residing somewhere in Russia. Meanwhile, documents collected by investigators have grown to 250 pages.
"Evidently it was a terrorist act. Not a criminal's revenge for some spoiled smuggling business," Algimantas Astaska, one of the special investigators at the time, told a local newspaper last week.
Investigators have long suspected Soviet OMON interior troops from the Delta unit in Riga.
On July 30, 1991, at about 3 p.m. a Soviet-made Latvia van full of heavy armed troopers ran the Lithuanian border at Salociai. Investigators believe it held OMON troops. Some of the troops later returned to Riga and some stayed in Vilnius.
Although many bullets were picked up at the scene of the crime, no guns were ever found.
Investigators believe the guns belonging to the murdered border guards were disposed of by Vladimir Razvodov, head of the Vilnius OMON unit, who is one of the prime witnesses in the case but is now in hiding in Russia.
Only after the coup in 1991 did the records of interrogations made by Soviet officials and other important information become available to Lithuanian investigators.
The slow pace of the investigation, which is now under the supervision of the Lithuanian general prosecutor's office, may be explained by the fact that Russia has consistently refused to cooperate in the search for suspects and the interrogation of witnesses.
During the commemoration, Lithuanian President Valdas Adamkus said that the Medininkai tragedy was one more test for the restored Lithuanian state and its devotion to the ideals of truth and freedom.
The organizers and the perpetrators of this brutal crime must finally be exposed and punished, he said.
"The sacrificed lives of the young men oblige us all to think and live in such a way that their sacrifice will never be forgotten."
The commemoration ceremony was attended by Parliamentary Chairman Arturas Paulauskas, Prime Minister Algirdas Brazauskas, Internal Minister Juozas Bernatonis, customs department Director Valerijonas Valickas and other officials. Sernas also participated.
A commemoration was also held at Vilnius' Antakalnis cemetery, where state leaders and other officials laid flowers at an elaborate memorial sculpted in 1991 to the memory of the murdered officers.
The people involved in the investigation believe then-Soviet Interior Minister Boris Pugo was involved in the assassination of the volunteer border troops in the breakaway Republic of Lithuania, and that Riga OMON chief Cheslav Mlinik discussed details of the operation with station chief Sergei Parfionov and Vilnius OMON station chief Vladimir Razvodov.
The leader of the Lithuanian Conservative Party, Vytautas Landsbergis, has suggested turning the case over to an international war crimes tribunal. Landsbergis registered the text of his draft resolution with the Lithuanian Parliament's secretary earlier this week.
The resolution calls on the government to form a special, high-level state commission to investigate the case.
The resolution also calls for appeals to international institutions for international arrest warrants to bring the suspects to trial in Vilnius or The Hague.
"The murder of detained and non-resisting Lithuanian state officials carried out on the Lithuanian border is an international war crime," the resolution reads. "Justice has not been done in this case."
During the period between Lithuania's declaration of independence and de facto recognition by the world at large, the nascent Lithuanian government symbolically placed volunteer officials at certain points along the as yet unmarked border with the Soviet Union. They had official instructions not to hinder movement across the border.