By Sara Sidner and Holly Yan, CNN

(CNN) -- Moments after R. Kelly pleaded not guilty to aggravated sexual abuse, the attorney for one of his accusers said there's more damning evidence against him.

Kelly, one of the most successful R&B acts of all time, was indicted on 10 counts of abuse of four victims, prosecutors said. Three of the accusers would have been underage at the time of the alleged crimes.

His attorney Steve Greenberg entered the not guilty plea for Kelly on Monday. Greenberg also said Kelly has turned in his passport -- though the singer doesn't have enough money to post $100,000 bail.

But attorney Michael Avenatti, who represents one of the accusers, said new witnesses and more videos indicate Kelly is guilty.

"Over the weekend, we have encountered a number of additional witnesses who we have interviewed, who we are in the process of preparing to meet with prosecutors," Avenatti said Monday.

"Each of these witnesses describe a decades-long system of abuse by Mr. Kelly of underage girls."

Avenatti also said there are two more videos that incriminate Kelly -- in addition to one previously viewed by CNN that shows a man who appears to be Kelly performing sex acts with a girl.

The first video shows actions that mirror some of the alleged acts for which Kelly was arrested for child pornography in 2002. Kelly was acquitted six years later.

On Monday, Avenatti said a second video has been turned over to prosecutors.

"The videotape depicts Mr. Kelly engaged in illegal sexual assault of a 14-year-old girl. It is approximately 55 minutes in length," Avenatti said. "It leaves no question as to Mr. Kelly's guilt on the tape."

The attorney said he has learned of a third video, but wouldn't specify what was on it.

No money for bail

Kelly, 52, will stay in Cook County Jail for the foreseeable future because he hasn't come up with enough money to bail out, Greenberg said.

On Saturday, Kelly's bond was set at $1 million. To leave custody, he'd have to pay 10% of the total, or $100,000.

But Kelly has had a spate of financial problems, including unpaid rent and unpaid child support.

"This is someone who should be wealthy at this stage of his career," Greenberg said last week.

He cited "mismanagement," "hangers-on" and "bad deals" as some of the reasons Kelly "really doesn't have any money at this point."

So for now, Kelly will keep going back and forth between jail and the courthouse. His next court hearing is scheduled for March 22.

Attorneys duke it out over credibility

The alleged abuse took place over 12 years, Cook County State's Attorney Kimberly Foxx said.

Prosecutors said there is a video that shows multiple sex acts, allegedly with Kelly and a girl who repeatedly refers to her 14-year-old genitalia.

But Kelly's attorney said he doesn't believe the accusers.

"I believe all the women are lying," Greenberg said.

Avenatti fired back at Greenberg, calling his statements "outrageous and completely unprofessional."

Singer owes thousands in unpaid child support

Kelly's surprising money problems go well beyond his inability to post bail.

According to court documents reviewed by CNN, Kelly owed more than $169,000 in unpaid child support to his ex-wife as of February 6.

The court ordered Kelly to make a monthly payment of $20,833 on January 8, 2009, but Kelly failed to show up to that hearing, per court documents.

To avoid being held in contempt of court, a judge ordered he pay $161,663 by March 6.

Greenberg told CNN his client "does not have to pay the child support before getting out."

Singer also faced eviction from his studio

Kelly also risked eviction from his Chicago studio last month because he owes more than $166,000 in unpaid rent.

Court documents show a judge signed an eviction order in January. The documents show Robert Kelly needed to move out on or before January 21, but Kelly was still at the studio minutes before he turned himself in to police on Friday night.

The eviction process began in July 2018 when the landlord, Midwest Commercial Funding LLC, said Kelly defaulted on the lease by initially failing to pay more than $79,000 in rent. The back rent continued to pile up, and the judge finally signed off on an eviction.

According to The Atlanta Journal-Constitution, Kelly also owes a Georgia property management company more than $31,000 in past due rent payments for two homes in suburban Atlanta.

Alleged victim has shirt with Kelly's DNA, prosecutor says

Under the terms of his bond, Kelly must surrender his passport and is forbidden from having contact with anyone under the age of 18.

During a hearing Saturday, prosecutors detailed the crimes Kelly is accused of committing, which allegedly took place between 1998 and 2010.

Foxx said one of the alleged victims gave authorities a shirt she wore during an alleged encounter with the singer, which later tested positive for Kelly's DNA. Prosecutors also alleged that Kelly spit on two of his alleged victims.