For six years, a serial killer prowled the streets of New York City, hunting his victims.

He promised to kill 12 people, one for each astrological sign, and the only struck while certain constellations were visible.

It took forensic astronomy, handwriting analysis, and the World War II code breaker defined him.

Late one, cold night in March 1990.

49-year-old Mario Arasco was walking home from his restaurant job in Brooklyn.

Without warning, he was shot in the back.

Mario survived, but he couldn't describe his attacker.

Three weeks later, there was a similar incident a few blocks away.

34-year-old factory worker, Hermann Monteney-Drow, was walking home after a serious night of drinking when someone shot him in the back.

He too survived, but he didn't see the gunman either.

Police recovered the 9-millimeter bullet.

There were no grooves on the bullets, and we're probably dealing with a zip gun type of homemade weapon.

Two months later, a short distance away in Queens.

78-year-old Joe Proci was about to open the door to his apartment when he was shot with a 9-millimeter zip gun.

Proci died later at the hospital.

This time, the killer left a note beside the victim.

It was a threat to kill 12 people, one for each astrological sign of the zodiac.

This is the the zodiac.

The 12 signs will die when the belts in heaven are seen.

The next day, a similar note arrived at the offices of the New York Post newspaper.

The killer called himself the zodiac.

The zodiac claimed responsibility for the three shootings, but he mistakenly believed that he had killed all three.

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