The Prosecutor General's Office said the probe was launched regarding the defamation of the memory of a dead person.
"In response to a request by chief prosecutor Simonas Minkevičius of Klaipėda Regional Prosecutor's Office, a pre-trial investigation was launched today regarding Klaipėda City Councilor Titov's statements on Lithuanian partisan commander Adolfas Ramanauskas-Vanagas," the prosecution service said in a statement on Monday.
During a municipal council meeting last week, Titov made his comments about Ramanauskas-Vanagas during a discussion on commemorating his memory in Klaipėda by putting a memorial plaque on the wall of Klaipėda University.
"Do you really think it’s worth honoring a person at whose initiative around 8,000 peaceful residents and children were killed? I believe there's no place for commemorating such people in Klaipėda," Titov said.
He also claimed Ramanauskas-Vanagas personally issued death sentences.
Titov also posted a similar post on Facebook on Jul. 19, and law enforcement plan to look into it as well.
Titov told BNS Lithuania on Monday he would be able to prove his claims with documents and personal testimonies.
Klaipėda Mayor Vytautas Grubliauskas says Titov could have breached the oath of a councilor with his statements and is initiating his impeachment.
A partisan resistance broke out in Lithuania in 1944 after the Baltic country was occupied by the Soviet Union for the second time.
Ramanauskas-Vanagas led partisans in the southern region of Dzukija. Together with other partisan commanders, he signed the Lithuanian Partisans Declaration of February 16, 1949.
Armed fighting for the restoration of Lithuania's independence lasted from 1944 until 1953. Ramanauskas-Vanagas was detained in 1956, brutally tortured by the Soviets and executed a year later.