The Chief Police Commissariat of Vilnius County said on Wednesday that the police had carried out searches and detained five men, aged 19-27, suspected of vandalizing the grave on 24 November, for 48 hours.
"Items and documents important for the pre-trial investigation were taken," the police said in a statement.
Last Saturday, the police received a report that a poster saying "Tomaševski Stop Doing Damage to Lithuania Or Your Place Will Be Here" was found near the grave, and later on, a carton box was also found with inscriptions "Poles Will Die", "Call the Cops", "Careful, Bomb" and "TNT".
Valdemar Tomaševski is leader of the Electoral Action of Poles in Lithuania.
Pilsudski is credited for his contribution to the restoration of Poland's independence after World War One. But in the Lithuanian memory, Pilsudski is often referred to negatively for his involvement in the occupation of Vilnius Region. His body is buried in Krakow, but Pilsudski's heart is in Rasų Cemetery in Vilnius.