(STNG) -  Mayor Daley's Michigan summer home was apparently the target of an arson that badly burned two of his neighbors' homes last month -- and was possibly set by someone angry over the recent killing by Chicago Police of a wild cougar on the North Side, the Sun-Times has learned.

The April 24 fire in Grand Beach, Mich., was initially believed to be an accidental brush fire. But police reopened the investigation after learning that a threatening note was sent to Daley's City Hall office, Berrien County Sheriff J. Paul Bailey said.

Bailey refused to release the contents of the note but said it led to the probe that eventually ruled the fire an arson.

Daley's home did not burn, but a source with knowledge of the incident said it appeared the fire was intended for his home and may have been tied to anger over the April 14 shooting of a cougar in Roscoe Village.

Winds pushed the flames to two other nearby homes, burning down one valued between $2 million and $3 million. A second home's garage was destroyed, officials said.

"It started right below Mayor Daley's house, but his house was not damaged, but it did get into the sand grasses and go over a sand dune and burn a house. Well, it was destroyed, and it burned another house partially," Bailey said.

The home that was destroyed belonged to Brad Griffith, vice chairman of the Chicago Board Options Exchange, and his fashion designer wife, Tiffani Kim.

After local police found out about the threatening note, they brought in outside investigators -- including the Michigan state fire marshal -- to take a second look at the fire, Bailey said.

Bailey would only say the targeting of the Daley home was "a possible part of the investigation."

FBI spokesman Ross Rice confirmed that FBI agents were sent to Berrien County this week.

"We're providing limited assistance to them as needed," Rice said. He would only say the matter was still under investigation.

Chicago Police are also cooperating with the FBI in the case, a spokeswoman said.

All of the affected homes were unoccupied during the fire, and no one was hurt.

Grand Beach police said a citizen first alerted them of heavy smoke coming from the Highpoint Ridge area, and the first police officer was on the scene at 12:40 p.m. on April 24.

That officer found a large field on fire, and the New Buffalo Township Fire Department was dispatched. They arrived at 12:54 p.m., police said.

The fire was apparently set on a grassy bank and spread rapidly northward toward the lake because of the winds, police said.

Ten days before the fire, Chicago Police shot a cougar after many sightings in the North Side neighborhood. Officers cornered the 122-pound cat in an alley and shot it seven times after it lunged at an officer.

Daley defended the officers' actions, ridiculing suggestions that the animal should have been tranquilized.

"I didn't see a neighbor running out and grabbing it and saying, 'I love you, oh come in the house,' " Daley said, wrapping his arms around himself in an embrace. "This is unbelievable."

The mayor's summer home gained its greatest notoriety in 1992, when a brawl broke out at an unsupervised beer party hosted by the mayor's then-teenage son, Patrick. The mayor and his wife were out of town at the time.

The mayor's father, the late Mayor Richard J. Daley, first purchased the family's lakefront compound in the 1960s. The mayor and some of his siblings continue to frequent the area.