"Kasab has killed so many innocent people. For how many days, should we take care of him is the question doing rounds in my mind," he said while addressing a gathering at a book release function here.
Patil said there was a need to set a timeframe to decide as to in how many days terrorists should be punished in a bid to send a strong message to those plotting and executing terror attacks in the country.
"The law is same for the people here and as well as for terrorists coming from across the border and killing innocent people. There is a need to give a thought about existing laws (so as to strengthen them)," he said.
Kasab was sentenced to death by a special court on May 6, 2010. The Bombay High Court upheld the sentence on February 21, 2011.
The lone surviving terrorist of the November 2008 strikes has challenged the HC verdict in the Supreme Court.
Patil released two books written on Mumbai's crime world by senior Marathi journalist Prabhakar Pawar. PTI VM RSY ZMN