In an interview with CNN-IBN news channel, Sherman also said that the Barack Obama administration would do everything possible to bring 26/11 mastermind Hafiz Saeed to justice.
Sherman, who earlier in the day met Foreign Secretary Ranjan Mathai, told the news channel that she understood the sentiments behind the 26/11 attack.
"There are processes of justice what both of our countries recognize. That's what is being played out with David Headley. He has been convicted. He is about to face sentencing and he is going to pay for his role in this heinous act. I hope Indians understand the rule of law."
To a question on extradition of Headley or Pakistani-Canadian Tahawwur Hussain Rana, Sherman said: "That extradition request is before the US now. I expect that there will be a ruling on that soon. I can't speak about the department of justice."
Speaking to the channel on the fourth anniversary of 26/11 Mumbai terror strike, Sherman said: "The US is very clear on that....we must do whatever we can to bring all of those responsible for such heinous act to justice."
"The US wants to do every single thing that we can to bring everyone to justice. We have announced the rewards for justice programme to bring the organizer of the attack - Saeed to justice. In this execution that just occurred, the US was very much engaged with India," she said.
"The FBI testified, we helped with forensic, with GPS location; we gave access to David Headley to Indian authorities. I think it's incumbent upon all of us to bring everybody to justice who had anything to do with this ordeal."
Headley had pleaded guilty in a US court to his involvement in the November 2008 terrorist attacks in Mumbai that claimed 166 lives. He had, however, entered into plea bargain with US authorities.
Sherman said the US's offer of $10 million bounty for Saeed is "one tool".
"Reward for justice is just one tool. It's a tool to say if people can come forward with information that can lead to conviction...we continue our work with Indian authorities, we raise this issue with Pakistan. This is just one tool among many things we are doing to bring everyone to justice."
"The US courts have convicted both Headley and Rana who, we believe, have been part of this. They are now waiting sentencing. So we don't believe in finishing till the job is completely done."
On a direct operation against Saeed, she said: "We are in the process of bringing him and others to justice...It's a part of the justice; we will pursue it and bring him to justice."
Sherman said Indian officials had "unprecedented access" to Headley. "As far as my understanding, the Indian authorities had substantial access to Headley. ..I'm sure our authorities stay in close contact on this matter and I will see what we can do to meet India's requirement. But my understanding is there has been unprecedented access for India."
On direct interrogation of Headley by India, she said: "My understanding is there has been direct cross-examination by Indian authorities of David Headley. What I can assure is that our authorities have been very responsive to Indian authorities and we will continue to do so."
New Delhi: US Under Secretary for Political Affairs Wendy Sherman said Monday that India's request for extradition of Lashkar-e-Taiba operative David Headley was under consideration and a decision could be taken soon.
First Published: Monday, November 26, 2012, 21:42