The notice said Guha made the "utterances" intentionally to bring disrepute to the RSS and BJP with an "ulterior motive" and the "direct allegations, insinuations and innuendos" impute criminal conduct.
It quoted Guha as having said in an interview, "It is very likely that her murderers came from the same Sangh Parivar from which the murderers of Dabholkar, Pansare and Kalburgi came." It also said Guha had made similar statements in an article.
The notice has been issued by Haranahalli Law Partners on behalf of State BJP Yuva morcha Secretary Karunakar Khasale.
Guha's comments were not immediately available.
Also Read
Noting that investigations were still ongoing in the deaths of rationalists Narendra Dhabolkar, Govind Pansare, MM Kalburgi and Gauri Lankesh, the notice also said no trial had taken place against any person, much less any conviction.
"Under such circumstances, without any basis or proof, you have given false and mischievous statements clearly calculated to defame our Client's organisation and its members," the notice says.
The notice demands Guha to categorically issue an unconditional apology within three days from the date of its receipt and to refrain from making any similar or identical statements or allegations.
It said if Guha failed to comply with the "instructions", civil and criminal prosecution would be initiated against him.
Gauri Lankesh, a harsh critic of Hindutva politics, was gunned down by unidentified assailants at her residence here on Septmber 5, with no clues on the incident so far.
Disclaimer: No Business Standard Journalist was involved in creation of this content