Empire State gunman did not plan to return to his apartment

Police found books on fighting skills and ammunition at the apartment of Jeffrey Johnson, the man killed in a police shootout at the Empire State Building Friday. Johnson had left his keys with his landlord Friday, and did not plan to return.

The man who shot and killed a former co-worker and was himself killed by police near New York City's Empire State Building had left his apartment keys with his landlord on Friday and did not plan to return home, a police source said on Sunday.

Jeffrey Johnson, 58, an out-of-work accessories designer, killed Steve Ercolino, with whom he had been feuding, on Friday morning in midtown Manhattan. Nine bystanders were wounded as the result of police gunfire, three of them hit by bullets and six injured by fragments caused when police hollow-point bullets ricocheted off concrete planters.

Johnson left his apartment on Manhattan's Upper East Side that morning as he always did, around 8 a.m., wearing a suit, neighbors said.

"He left the keys in an envelope for the landlord with no intention of ever coming back," said a police source familiar with the investigation who declined to be identified because the source was unauthorized to speak publicly about the details.

Detectives searching Johnson's apartment found books on training and fighting skills such as "Techniques and Equipment of the Deadly Marksmen Snipers" and "Attack Proof - the Ultimate Guide to Personal Protection," the source said.

They also found a plastic case with 15 rounds of .45 caliber ammunition, the same kind he used to shoot Ercolino, and police planned to examine the contents of Johnson's home computer for more clues to his motive, the source said.

Johnson was being threatened with eviction, the New York Post reported on Sunday.

Johnson had been laid off a year ago from Hazan Imports, across the street from the Empire State Building, where he was locked in a dispute with the victim, police said. Johnson claimed Ercolino had failed to sell enough of his creations and held a grudge, they said.

Animosity between Johnson and Ercolino had prompted them to file complaints about each other with police in April 2011, police said.

Ercolino, 41, was a salesman at Hazan. He lived with his girlfriend in Hoboken, New Jersey.

Reporting by Chris Francescani; Writing by Ellen Wulfhorst; Editing by Daniel Trotta and Vicki Allen