"On April 2, a report was received that the letters 'V' and 'Z' had been written overnight on some of the memorial's monuments," Julija Samorokovskaja, spokeswoman for Vilnius County Police, told BNS.
"The report has been included in the ongoing pre-trial investigation," she added.
Last Friday, the police said the Paneriai complex had been defaced with "Z" and "V" symbols of Russia's invasion of Ukraine, adding that they had opened a pre-trial investigation into the violation of public order.
Ruta Ribinskaite of the Jewish Community of Lithuania said it was a fresh attack, because the letters had been removed after the first act of vandalism.
Paneriai is the largest site of mass killings organized and carried out by the Nazis in Lithuania. Some 50,000 to 70,000 people, mostly Jews from and around Vilnius, were killed there between 1941 and 1944.
The Z symbol has emerged recently after Russia started its invasion of Ukraine.
The Russian Defense Ministry explained in early March that the letter "Z" on military equipment stands for "Za pobedu" ("For victory"), while the "V" symbol stands for "Sila v Pravde" ("Strength is in the truth") and "Zadacha budet vypolnena" ("The task will be completed").