The sisters of Joanna Speaks, an Oregon woman who was found dead in Clark County, Washington back in April, are speaking out after Portland Police Bureau officials said they don't believe there is a connection between six women recently found dead in the region.

“Nobody can rule out that they're not connected, because no one has enough information,” said Ariel Hamby, one of Speaks’ sisters.

Last week, Speaks’ death was ruled a homicide by the Clark County Medical Examiner's Office.

“Knowing what the cause of death was is huge,” said Robyn Speaks, another sister.

The last time Ariel Hamby and Robyn Speaks spoke to Joanna was on March 15. They say she was homeless and using drugs.

On April 8, her body was found in an abandoned barn in Ridgefield.

Since then, it's come to light that authorities have found the bodies of five other women in the last 3 months, within 100 miles of each other.

It's also been reported that several of the women, like Speaks, were homeless and using drugs, including Bridget Leann Ramsey.

Speaks' sisters say Ramsey was a friend of Joanna’s in grade school and the two had recently reconnected.

Ramsey's body was found three weeks after Speaks’, near Mill Creek in Polk County.

On Sunday, Portland Police released a statement saying they don't believe the deaths of the six women are linked.

The sheriff’s offices in the four counties where the bodies were found have not come to the same conclusion.

“We’re just asking for people in that demographic, the homeless, mentally ill, addicted to be careful because you can't say that they're not connected. We don't have the proof that they're not connected,” said Hamby.

So far, only Speaks’ death has been ruled a homicide.

A spokesperson for Portland Police said the FBI is not involved in the investigation.