Who Done It?

As the midnight train arrives at the station, Art Ferrelo appears to be sleeping in his seat.

Someone knows that is not true.

At the station, four other passengers get off the train, leaving poor Art behind. The conductor comes and taps him on the shoulder to wake him, but quickly realizes he won't be waking again. He is dead.

"His heart?" asks the inspector.

"Strychnine," answers the forensic doctor.

A few hours later, the four other passengers have been rounded up and are being questioned.

The man in the dark suit: "I'm innocent. The blond woman was talking to Ferrelo."

The blond woman: "I'm innocent. I did not speak to Ferrelo."

The man in the light suit: "I'm innocent. The brunette woman killed him."

The brunette woman: "I'm innocent. One of the men killed him."

Later that morning, while filing the paperwork on his arrest, an officer asked the inspector how he had solved the case so quickly.

"It was easy," answers the inspector. "Four true statements and four false ones. Easy as pie."

Who killed Ferrelo? (Only one person is guilty.)