The convoy began journey from N S C Bose International Airport after Jaitley boarded his car on way to Dalmiya's house to meet his family members, a senior city police officer said.
Accordingly, the Special Branch, wireless and all police stations through which the convoy was scheduled to pass were informed.
"But after the convoy left behind AJC Bose Road flyover, the minister's car suddenly deviated from the route and took a turn towards Raj Bhavan.
"It was the VVIP who had decided suddenly to go to Raj Bhavan first before proceeding towards Dalmiya's house."
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The City Police Special Branch (SB) sources said the communication could not be maintained perhaps because of the jammer in the convoy.
However, the pilot car later returned to Raj Bhavan and took the minister to Dalmiya's house at 10 Alipore Road over half-an-hour behind scedule.
Dalmiya died in a city hospital on Sunday after suffering a massive cardiac arrest.