"I don't know about his arrest. His phone is switched off. Now we have decided to go there," M Biswas who lives in the eastern fringe of Kolkata said.
The police has not contacted him, he said.
The senior Biswas said he did not believe that his son had any link with ISIS.
"One reporter asked me about it last night. Then I contacted him and
M Biswas, who used to work for State electricity board, said "My son is busy with his office duty from 8.45 in the morning till night".
Asked if he know that his son used to tweet in support of ISIS, he replied, "I don't know. But he told me that some people came to him from Channel 4".
On whether he supported ISIS, the senior Biswas said "I don't know what is ISIS. There is no question of supporting it".
Karnataka Director General of Police L Pachau told reporters in Bengaluru that Mehdi Masroor Biswas had 'confessed' he was handling the pro-jihad Twitter '@ShamiWitness' and he was particularly close to English-speaking ISIS terrorists.
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