Why did several people say they saw Robert Perry there?

When police interviewed Columbine students after the shooting several of them said they saw a former school acquaintance of Harris and Klebold, named Robert Perry, at the school that day. I read that Perry had dropped out of school a few months before the shooting and wouldn't have had any real business being there.
Robert Perry lived within walking distance of the school and these witness statements caused his home to be searched by the police. There seem to be quite a few people who say they saw him there, versus his mother and grandmother claiming he was home at the time.
How could these people all be lying or making a mistake?

Robert Perry was very similar looking to Dylan, even being around the same height. Couple that with him being known as a member of the Trench Coat Mafia, and you can see why so many people's brains registered him as the shooter. As to the possibility of him being there or of there being other shooters, there are a lot of witnesses who reported seeing shooters that didn't match the description of E+D, but eyewitnesses are notoriously unreliable. If you're getting fokin' shot at, your brain is gonna be too confused to accurately describe who was shooting at you. No way he'd get away with participating in a school shooting either, and all of the evidence points towards E+D being the only two shooters.

I do think that there were were people in E+D's circle who knew it was gonna happen, and maybe some of them participated in the planning in some capacity. I mean if they tried to recruit Chris Morris, surely they tried to recruit other ppl...

My theory is that the cops had some ideas as to friends of E+D who may have been privy to their plans, but never got enough concrete evidence to arrest them.

vril wrote:

I mean if they tried to recruit Chris Morris

They did? I haven't heard this, do you have any links that explain this?

I'm curious if Robert Perry actually WAS there, but he was just hanging out and happened to be at the wrong place at the wrong time