Hardin spoke with ESPN on Monday about the progress of the criminal and civil cases involving his client.
"There are 10 women that have made complaints to the [Houston] police," Hardin said.
Eight of the women, according to Hardin, are among the 22 women who have alleged in lawsuits that Watson sexually assaulted them or engaged in sexually inappropriate behavior during massage sessions.
Two of the women who have filed complaints with Houston police, Hardin said, have not filed lawsuits against Watson.
"There are a couple of women who we don't know anything about," Hardin said.
Hardin acknowledged knowing the names of the 10 women who have filed criminal complaints, including the two who are not involved in civil litigation, but declined to provide those names to ESPN.
Houston police would not comment when reached Monday on either the investigation or the number of women who have filed complaints.
Hardin said Watson and his legal team have fully cooperated with Houston police and with the Harris County District Attorney's office.
"We're dealing with both of them, providing them information," Hardin said.
"We're fully cooperating with the police. We're fully cooperating with the district attorney's office and, when the criminal investigation is over, we'll fully cooperate with the NFL."
Investigators with the NFL have yet to interview Watson, which is typical in an ongoing criminal matter, Hardin said.
"We've made it clear to the NFL that we'll totally cooperate with them when they're ready to visit with us. But they, out of deference to the criminal investigation, always try to wait until that's completed before they try to talk to the accused person."
In a statement released to ESPN on Monday, Houston attorney Tony Buzbee, who represents the 22 women suing Watson, said he and his legal team continue to handle "22 civil cases that make very serious and specific allegations."
"As of today, almost half of these women have given sworn statements to the police, and almost half have spoken to the NFL's investigative team. Both processes are very lengthy. We expect to provide further information to the NFL from all victims," Buzbee said.
With respect to the pending lawsuits, Hardin said that while both sides have exchanged documents, they have yet to schedule depositions for the 22 women. Under an agreement between the legal teams, depositions for the plaintiffs will begin in September. Watson won't be deposed until February of next year.
"It is really going the normal course of all civil litigation," Hardin said of the depositions. "The dates haven't been set as of yet, the exact dates as to who would go when. But they'll start in September."
If Watson were to reach a settlement with any or all of the women who are suing him, Hardin reiterated his desire to make any settlement public and said Watson would not sign any settlement that includes a confidentiality agreement.
"I do not want anybody to be saying that this guy paid off women to stay quiet and so, if there ever was a settlement of any kind, it would have to be public and therefore both sides, [Watson] and the women, would be able to say to the world at large whatever they wanted."
Hardin acknowledged Monday that he is not involved in any way in the decision-making process with respect to Watson's football future.
The Texans quarterback has been the subject of trade rumors for months, even before the off-the-field legal battles this offseason.
"Teams are ready to jump now if the Texans would trade with them, even while all this is pending," Hardin said. "There's no question that teams, numerous teams, are still interested. The ball is in the Texans' court."
"As far as Watson's football career," Buzbee told ESPN, "I'm not focused on whether Watson will play; I'm instead focused on the welfare of the women he had contact with and aggressively pursuing their cases in court."
ESPN's Michael Rothstein contributed to this report.