It’s not clear – but Dan Roth, a pastor at Summerfield-Siloam United Methodist Church in Fishtown/Kensington stayed on the safe side by calling police Sunday morning when he found copies of a cryptic letter believed to be written by the Zodiac Killer tucked under the windshield wipers of two parked cars.

"I can’t really say that I was afraid," he said. "But, I thought caution was the best thing."

Roth said that he was heading to church around 10 a.m. Sunday when he saw the copies of the letter allegedly written by serial killer in 1970 that had a series of symbols. It read:

This is the Zodiac speaking.

I have become very upset with the people of San Fran Bay Area. They have not complied with my wishes for them to wear some nice Zodiac Killer symbol.svg buttons. I promiced to punish them if they did not comply, by anilating a full School Buss. But now school is out for the summer, so I punished them in another way. I shot a man sitting in a parked car with a .38.

The map coupled with this code will tell you where the bomb is set. You have untill next Fall to dig it up.

Whoever placed the notes there worked somewhere between 1:30-10 a.m., Roth said, since he didn’t notice anything when he got home late Sunday morning.

The Zodiac Killer, whose exact identity remains unknown, conducted a string of murders in Northern California between the 1960s and 1970s. He would send strange letters, coded in cryptograms, detailing the crimes to San Francisco media outlets, thus earning the nickname.

Roth said that while he’s certain that this is some kind of hoax and that the serial killer hasn’t emerged in Philadelphia more than 50 years later, he called the police given the threatening content of the letter.

"As I gave my story to the police officer, he got a call saying that there were a few others," Roth said.

The officer who took Roth’s statement said other notes were left on Sepviva Street, though, Philadelphia police Sgt. John Massi of the 26th District couldn’t confirm reports of others. Police are currently monitoring the situation.

Massi said he’s pretty sure that this was an eerie Halloween prank just a few days before the holiday, but will escalate reports to central detectives if there’s a continuing pattern or more direct threat.