I don't think Don Harmon was ever a suspect. 

There's a really interesting 2004 interview on the homepage under "A Tribute to Jim Feldhaus," a recently deceased private investigator who spent years looking at Jodi's case. He never says a name, but does give several hints about who he thought was involved in Jodi's disappearance. And the person he alluded to throughout the interview wasn't Don Harmon.

I would have liked to hear his Mr. Feldhaus's thoughts about the red Mazda Miata Jodi acquired from an area businessman the same month she disappeared. Imho, that acquisition started the cascade of events that culminated in Jodi's disappearance and probable murder. 

It was also interesting to hear how puzzled Mr. Feldhaus was over why Jodi's body has never been found. He says this is very unusual, which, to me, lends more credibility to the idea that Jodi's body is either underwater or, maybe in an abandoned underground area, like an old well or cistern. This could also be the final resting place of Jodi's briefcase, which apparently disappeared with her. 

Anyway, it's well worth 20 minutes to watch this interview. 

the picture on the home page of Jodi's friends eating pizza, Is that Dustin Honken in the light blue denim shirt?