Dead Woman's Family Denies Suicide, Says Cops Blew It

Jan. 13, 2014— -- The family of a Michigan woman found dead in a river four years ago says local police were wrong to rule her death a suicide, citing new evidence uncovered by a private investigator.

JoAnn Matouk Romain, 55, disappeared after leaving a Grosse Pointe Farms, Mich., church January 2010. Her body was discovered more than two months later floating in the Detroit River near Canada.

Police ruled Romain's death a suicide, claiming she drowned herself. But Michelle Romain says she thinks someone killed her mother.

WATCH: Woman Out to Show Mom's Suicide Was Murder

Romain said she believes someone followed her mother, perhaps someone with a vendetta against another family member.

"I never for one second believed that my mother committed suicide," Romain told ABC News. "There are many clues that show there's foul play involved."

Frustrated by what she believes is a botched police job, Romain hired a private investigator.

"JoAnn Romain did not commit suicide," private investigator Scott Lewis told ABC News affiliate WXYZ-TV in Detroit. "I believe there was foul play. In short, I think this was a murder."

Among the perceived clues the family points to are JoAnn Matouk Romain's high-heeled boots that she wore the night she died. Romain walked over two concrete ledges and metal rods before walking into the rocky river, authorities have said.

But Michelle Romain says that other than some clay from the river, her mother's boots were in impeccable condition, consistent with her being carried.

According to the daughter, her mother's purse had rips in it that weren't there the morning before she disappeared, and an autopsy indicated there were bruises on her upper left arm, the same arm where she carried her purse, Romain said.

Romain said her mother fueled her car the same day she disappeared, wondering why a woman who intended to kill herself would bother with gasoline. The daughter also pointed to the location of her mother's car, which, she says, was found in a different parking spot from where her mother originally parked the vehicle at the church.

Police have reportedly said they stand by their initial findings, although they say they are willing to review any new evidence.

"It would take substantial new evidence for the police to reopen a case," former FBI agent and ABC News consultant Brad Garrett said. "Like the identity of a killer and perhaps evidence as to the particulars of her death."

Meanwhile, Romain and her brother say they won't stop fighting.

"We will not rest until her … killers are found," Romain said, "and justice is brought."