Police in the Detroit suburb of Eastpointe are trying to determine whether suspicious fires in a house are tied to letters sent earlier this week to black homeowners warning them to "move back" to the city or be killed "one by one."
The ominous letters arrived in mailboxes in a two block area of the middle class town on Tuesday.
If they didn't move, they would be "killed one by one," the letter threatens. A copy of the letter was obtained by ABC affiliate WXYZ.
Fears were heightened by a pair of fires in one of the homes Thursday evening.
Interim Eastpointe Fire Chief Bob Niedermaier told ABCNews.com that firefighters responded to a call at 6:17 p.m. on Sprenger Avenue. Firefighters found beds in flames in two bedrooms of the house, which had damaged the beds and dressers in each room.
By today, investigators had eliminated mechanical and electrical problems as potential causes, but fire investigators are trying to determine whether or not the fire was accidental or intentional.
"It's suspicious because you don't normally have a fire on top of a bed," Niedermaier said. The fact that the two fires were separated within the house is another reason the fire is suspect, he said.
Eastpointe police are trying to determine who sent the letters and are joined in their investigation by the FBI and the U.S. Postal Service. The letter was handwritten and each person received a photocopy of the same letter.
"Seventeen addresses were listed in the letter," Eastpointe Detective Lt. Scott Bourgeois told ABCNews.com. "Right now, we're unsure of how many of those letters were actually mailed out."
Det. Lt. Bourgeois described the neighborhood as "diverse," and noted that some of the people who had received the letter were not African-American.
What prompted the mailings remain a mystery, he said.
"There's no indication why somebody would send this letter out at this time," Bourgeois said.
Niedermaier said police are now investigating whether the fires and the letters are linked, but the fire chief has his doubts.
"I have no reason to connect the fire investigation to the letters," he said.
The letters have been sent to a state crime lab for forensic testing and evidence from the fire has also been collected for analysis. Officials hope that results from these tests will help them determine if the fires were intentional and who sent the letters.