'Whitney & Bobbi Kristina' Biographer Claims 'Nick Gordon Is Shaking in His Boots'

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Following an earlier sighting at his Florida duplex on Thursday, Nick Gordon was last spotted running away from reporters in Florida when asked about Bobbi Kristina Brown.

On Wednesday, after news broke that Bobbi Kristina had been moved to a Georgia hospice center as her health continues to deteriorate, Bobbi Kristina's court-appointed conservator, Bedelia Hargrove, filed a lawsuit accusing Gordon of physically abusing her and stealing thousands.

NEWS: Bobbi Kristina Brown -- A Tragic Timeline

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A source tells ET that Gordon is trying to stay out of the limelight during this difficult time for Bobbi Kristina’s family and remaining close by the duplex he shares with his mother, Michelle. The 25-year-old has also been surrounding himself with friends that live in his gated community -- one female friend and two male friends. Gordon has also been spotted using the complex's gym and hot tub.

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Meanwhile, ET spoke on Thursday with Ian Halperin, the author of the unauthorized biography, Whitney & Bobbi Kristina: The Deadly Price of Fame, who claims Bobbi Kristina and Gordon had a very explosive relationship.

PHOTOS: Bobbi Kristina's Cutest Childhood Pics

"This is a clear-cut case of negligence, of abuse, of foul play," Halperin claims. "And right now, Nick Gordon is shaking in his boots. I have spoken today to members of Bobby Brown's family, and they want justice immediately."

Halperin claims Gordon stole far more than the $11,000 he's accused of in the lawsuit of taking while Bobbi Kristina was placed in a medically induced coma.

"They had joint accounts. Nick insisted on it," Halperin alleges. "There were fancy cars. There was fancy jewelry. There were trips. We won't know until a proper investigation is done. But I'll tell you right now it's much more than $11,000."

NEWS: Brown & Houston Families Visit Bobbi Kristina at Georgia Hospice Center

According to Halperin, the troubled pair had issues with drugs.

"I have incontrovertible evidence the last few months they were together, they were on drugs almost all the time," he claims. "It's just proportion to heights nobody could even imagine. And drugs were prevalent in their lives. ... They got completely out of hand and it was a ticking time bomb."

NEWS: What Hospice Care Means for Bobbi Kristina

ET recently talked to former LA prosecutor Michael Kraut, who weighed in on possible charges Gordon could face, given the serious claims against him in the lawsuit. The lawsuit alleges that Bobbi Kristina set up a meeting with an unnamed person on Jan. 31 to discuss that Gordon was "not the man she thought he was," and was later found unresponsive in a bathtub that same day, "face down, with her mouth swollen and another tooth knocked out."

"[The District's Attorney] will have to make a decision whether this was a homicide, a domestic violence or non-criminal," Kraut explained. "Nick clearly doesn't have $10 million. The lawsuit was filed to get information in order to provide the police and district attorney about what happened on that day."

For his part, Halperin echoes claims made in the lawsuit.

"That particular night, hours before Bobbi Kristina was found unresponsive, Nick and Bobbi had a massive argument," he claims. "There was violence. And Bobbi Kristina didn't mince words."

NEWS: Dr. Phil on Nick Gordon -- 'Give Him a Chance to Tell His Side of the Story'

Watch the video below for more on the lawsuit Gordon's facing.

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