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MUNCIE, Ind. — Michael Coates would have turned 42 on Thursday, but his family is unable to celebrate with him.

His body was found at the Muncie wastewater treatment plant back in May, but police and his family are still left wondering what happened.

“Half the time I cant sleep,” said Teresa Dodd, Coates’ older sister. “It just doesn’t … it doesn’t ever go away.”

Losing her younger brother was hard enough, but not having answers only makes it worse.

“I think that’s the hardest part, you know,” said her husband Dave Dodd. “Not having really any closure.”

“Didn’t get to say goodbye,” Teresa added.

Coates was last seen Sunday, May 19th at his home in Muncie. The next day, workers found his body inside the Muncie wastewater treatment plant. His family says he was missing his shirt, shoes, hat and cell phone.

“I really didn’t want to believe it,” Teresa said. “When they showed me the pictures I just didn’t think it really was him.”

Both police and the family believe this case was no accident. Police say they walked through the plant and could not find any way Coates could’ve gotten into the system by himself.

“I’ve lifted weights most of my adult life and I’m not strong enough to climb into one of those holes and then pull the manhole cover back over top of me,” Capt. Todd said. “We’re confident that didn’t happen. We feel he was either thrown in at the plant, which are two open cylinder pools, or he was thrown in and they put the cover back over him.”

The autopsy results also don’t make the case any clearer.

“That’s kinda the problem,” Capt. Todd said. “We thought maybe the pathologist would give us an official cause of death. But due to the circumstances of where he was found with the water and with the injuries … they could not come to a conclusion.”

“Something happened and somebody knows, and they’re not coming forward,” Capt. Todd added.

No matter what happens, Coates 16-year-old son will grow up without a father as Teresa will have to live without her brother. Her birthday post today on his facebook page will go unanswered, as she waits for another answer.

“It’s not going to make it completely better, it’s not going to bring him back, but I think we really need it,” Teresa said of answers.

“We don’t want to let it go. It’s harder on the family,” Capt. Todd said. “They want an answer, they want to know what happened to their brother, their son … and we want to provide that. We just need more information to go on.”

If you have any information on Coates whereabouts on Sunday, May 19th before his death, contact the Muncie Police Department or Muncie Crime Stoppers at (765) 749-4933. You could be eligible for a reward up to $1,000.