Cecilia Reyes spoke to media Thursday after meeting with District Attorney Richard A. Brown.
"I just want justice, and I want it to be done the right way," Reyes said.
Polanco was shot by Detective Hassan Hamdy last week. No weapon was found in Polanco's car.
His lawyer says Hamdy fired after he saw Polanco reaching under his seat. He said Polanco didn't comply with Hamdy's orders to put his hands up.
A front-seat passenger in Polanco's car disputed that account, saying Polanco had no time to comply.
Civil rights lawyers Michael Hardy and Sanford Rubenstein accompanied Reyes for her half-hour meeting with Brown and several prosecutors from his office.
Hardy said Brown offered his condolences to Reyes.
"All you can hope for in any investigation is that they do it thoroughly, that they do it impartially, that they put the best people that they have available to them on it and they prosecute it with the interests of the people of this borough," he said.
Brown issued a statement after Thursday's meeting, saying the investigation is ongoing.
"Our decisions in this case will be based solely on the facts and the law and that we will follow the evidence wherever it leads us. I assured them that our investigation is active and ongoing and that it will be completed as expeditiously as possible. I pointed out, however, that the investigation is still in its early stages," Brown said. "I told them that when we conclude our investigation I expect that we will present all of the facts to the grand jury."
Police Commissioner Raymond Kelly said he expects the case to be presented to a grand jury, as well. "Not all cases actually go before the grand jury, but this case I believe needs to go before the grand jury," Kelly said Thursday.
Polanco's funeral will take place Friday in Corona. Reverend Al Sharpton is set to deliver remarks.
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