The lawyer for Michael DeHerrera, the Denver man seen beaten on police surveillance video in April of last year, said it took four months and two subpoenas to obtain the video that ultimately cleared DeHerrera of any wrongdoing.It was surprising to us that it could take that much time, said attorney Tim Edstrom.Edstrom said city officials told him repeatedly that the video was no longer available because it had been rolled over and erased after 30 days, per city of Denver policy.But Edstrom persisted. This seemed like something they should have caught on the video, he said. We believed that it must be out there somewhere.It was. Edstrom said city officials discovered that the video did exist, and within moments of showing the images to city attorneys, DeHerrera was cleared.Steve Zansberg, a first amendment rights lawyer, said unfortunately, the situation is not unique.It isn't that uncommon that agencies say 'We no longer have those records. They've been purged.' And lo and behold, they do, said Zansberg.City Council President Chris Nevitt said the city may need to examine whether to extend the length of time that the city is required to keep HALO video before it is erased.Keith Johnson said a policy change might have prevented the loss of video that he claims shows a Denver police officer using excessive force while arresting him last January. Johnson said the arrest happened at an RTD bus terminal on Federal Blvd. and Colfax Ave., in full view of several HALO and RTD surveillance cameras.I have been trying to get this video evidence from day one and told that it doesn't exist, said Johnson.In a statement, the officer who arrested Johnson claimed Johnson shoved him, causing him to break his ankle. But Johnson was later cleared of assaulting a peace officer and instead charged with a lesser crime, resisting arrest.Johnson said the video would clear him of that charge, too, but Johnsons lawyer has been repeatedly told that the video showing the incident was erased.Johnson said in May the city released a portion of the video, but it shows only the aftermath of the arrest, not the scuffle leading up to it.Zansberg said Colorado law allows law enforcement to restrict access to HALO camera video as long as authorities explain why it would not be in the public interest. But Zansberg said that should not stop people such as Johnson from getting access to the video.A victim of an assault ought to have access to these records that document the assault, said Zansberg.Johnson said he firmly believes that the video documenting the January incident does exist, and he still hopes to hunt it down before his October trial.Im still fighting for the video, he said.