WARREN, Mich. -

Warren police say DNA tests confirm that body parts discovered last year in Macomb County are from two white females.

Workers repairing a massive sewer line found 10 body parts in Sterling Heights last August. In December, two more pieces were discovered the same way in the sewer at Schoenherr and 10 Mile roads in Warren.

“The fact that it comes from different persons makes us more aggressive in our investigation," said Warren Police Commissioner Jere Green. "We need answers."

Green says the DNA profiles were searched in national DNA data bases, and did not match. Missing persons reports don’t connect either.

Investigators are once again showing images of tattoos from the Sterling Heights victim, hoping they jog someone’s memory. The case will probably not be solved unless the victims are identified.

"There’s no investigative blueprint to investigate this kind of situation," said Green.

Police have investigated whether the body parts are medical waste, disposed of illegally. They haven’t ruled out that scenario, but believe it’s unlikely. They consider this to be a homicide case.

Green believes the body parts are from adults. The women may have been be heavy-set.

No one can be sure where the body parts entered the sewer, which flows through northern Macomb and Oakland Counties. The parts are no more than four inches square, meaning someone could have put them into the system at a home or business.

Read more: Police: Tattoo on body parts inked 15-20 years ago

“We haven’t been able to narrow down a time frame, but we know they couldn’t have been in the system too long because of the temperature down there,” said Green.

Anyone with information is asked to call Warren police or Sterling Heights police.