Attorney Ben Crump held a news conference at Jack Johnson Park in Galveston Monday morning.
Crump has been retained to represent Donald Neely after a photo of Neely went viral. He said he wants to know the officer's demeanor and language leading up to the image from the now viral video.
READ MORE: Galveston officers on horseback seen leading handcuffed man with rope
"If that video comes out, and it affirms what the witnesses said that they treated him, and mainly that they use derogatory terms towards him, then we need to have a march to demand equal justice," Crump said.
If the video is not released by September 15, he is calling on activists to descend on Galveston for a march.
"If the officers were of good character, the Galveston Police Department should have no problem releasing the body cam footage of the incident," said Crump. "If they don't release it in 30 days, we are going to invite other civil rights advocates to come and march in Galveston."
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Neely himself was not in attendance. His criminal defense lawyer, Melissa Morris, said Galveston police charged him with trespassing, but they're still waiting to see if the Galveston district attorney's office have accepted those charges.
Neely's brother and sister took time to speak about their brother, saying despite his mental illness, Neely was there for his family.
"He's not a bad person. He's very loving. He's just the sweetest thing on this earth, he's just mental," said Neely's sister. "He just lost his way somewhere and just ran off and there was nothing we could do about it."
The Galveston city manager and the Galveston police chief announced last week that the Texas Rangers are conducting a criminal inquiry into Neely's arrest.
The video will not be released until that investigation is complete.
The City of Galveston released this statement in response to Crump's demand for body camera video:
"The Galveston Police Department remains committed to a thorough, complete and timely review of all the facts related to Mr. Neely's arrest. As such, the department has asked the Texas Department of Public Safety's Texas Rangers Division and the Galveston County Sheriff's Office to perform independent investigations of the August 3rd arrest of Mr. Neely. This review is now with those agencies and we have full confidence they will thoroughly and justly evaluate the incident. We anticipate the body camera footage will be released after the investigations are concluded. The Texas Occupations Code (Sect. 1701.660) prohibits the release of the videos before that time. These investigations will be reviewed by the Galveston County District Attorney's Office."
On Aug. 3, a photo was captured showing Neely being led on a rope by two mounted officers on horseback for six blocks.
He was arrested in the 600 block of 23rd Street and walked to 21st and Market. People took pictures and video. The images have been compared to those from the dark days of slavery.
READ MORE: Texas Rangers investigating man's controversial arrest by officers on horseback