In the images below, when Dia goes missing Diane Fedder immediately claims to be the power of attorney and says to have all information and details go to her. She sets up a sale to sell Dia's stuff right after she goes missing. Diane Fedder claims she will hire a private detective. To my knowledge a private detective was never hired by Keith Harper and/or Diane Fedder. Keith Harper only ever mentions the free psychic service that he used. Diane Fedder then claims that "we have offered a reward for her return." The only reward that was put out was from Keith Harper of $10,000 "for her safe return." They knew that she was never going to return safely.
Some of the items listed seem very valuable.
Diane Fedder says the police have no leads, right when Dia disappeared the police issued search warrants on Keith Harper, it would be incorrect to state that after Dia went missing there were absolutely "no leads." Diane Fedder being an ex-secret service agent, knowing about Keith Harper's sex offender status and him fleeing the scene, his statements that he was the last person to see her alive, and him being the supposed "spouse", I would imagine that it wouldn't be difficult for an ex-law enforcement official to see that there was at least one lead but she aligns herself with Keith Harper by claiming they issued a reward and were hiring a private detective. So it would make sense that she would try to sweep Keith Harper being a lead under the rug and keep the situation and her partnership with Keith Harper hush hush, pretending "there is nothing to see here."
In my humble opinion, they committed this murder together, and had the help of others as well on the corpse disposal.