Artist, author, and retired detective Joe Getsinger says Sally Snickers' pigtails point the way to "the bigger story of the King of Cartoons."

While doing research for a soon-to-be-published book, Getsinger found an early iteration of the distinctive Sally character in a 1930s comic strip by Jack Kirby, later the creator of Captain America, the Fantastic Four, and many more.

"Sally helped me connect the dots" between Kirby's formative years and his fame, says Getsinger, who discovered the revelatory images within his collection of about 8,000 printing plates.

He describes these letterpress plates - composed of zinc with raised surfaces that transfer ink to paper - as "masters" for printing cartoons in newspapers during the mid-20th century.

"Left in a warehouse, they would have oxidized," Getsinger, 66, says, showing me around his Woodbury Heights studio.

"They could have been scrapped."

Instead, the plates - utilitarian, yet exquisite to my print-loving eyes - provide a window into the creative, competitive, and collaborative ferment among rising cartoonists in 1930s New York.

"These are young guys at a critical time in the publishing world," says Collingswood comics historian Richard Greene, noting that Depression-era newspapers were running page upon page of comics, and comic books were about to enter their first golden age.

The collection includes early strips and single "gag" panels by Bob Kane (who later gave us Batman), Will Eisner (The Spirit), and Jerry Iger (perhaps best known for his pioneering comics distribution partnership with Eisner).

The plates showcase the work of cartoonists who became known - including Ruth Roche, among the few females in the field - and those who remain obscure.

But collectively, they produced an abundance of content for an emerging medium that both mirrored and helped define the time.

"Movies are [still] being made about the characters they later created," says Greene, a graphics designer who has a collection of cartooning-related art on exhibit at the Cherry Hill Public Library.

He also contributed to the author's forthcoming book about Eisner.

Getsinger, who retired from the New Jersey State Police as a detective sergeant in 1996, has a boy's enthusiasm, an archivist's mind for details, and a sleuth's tenacity.

He painstakingly inks the plates, handprints copies, digitally scans them, and pores over long-lost, born-again comics with names such as Prattle and Tattle and Jest Laffs.

After figuring out who's who (many cartoonists published under multiple pseudonyms), he documents the evolution of individual artists, and the art form they made into an enduring pillar of pop culture.

"I'm intrigued by the transitions in style, from cartoonish to realistic," Getsinger says.

Locust Moon Press in West Philadelphia, which had great success in 2014 with the Little Nemo: Dream Another Dream anthology, is set to publish Getsinger's The Lost Works of Will Eisner this year. The author's Kirby volume will follow.

"Joe has a treasure trove of fascinating stuff [that] shows Eisner developing his own, one-of-a-kind voice," publisher Josh O'Neill says.

"Eisner was one of the architects of the modern comics language," O'Neill continues. "He invented the graphic novel. . . . These [early] strips have never been collected, and some may never have been published."

Getsinger, who drew his own comic strip, about car-crazed "motorheads" while a student at Camden's Woodrow Wilson High School in the 1960s, says studying the plates can be like discovering secrets.

Such as when he figured out that Kirby, and not "HT Elmo," created Sally Snickers.

Turns out the cartoonist had a tiny typographic signature - a hash mark for whatever name he was using for a particular strip at the time.

"He was leaving a clue," Greene says. "A clue for a detective in the future."

Now there's a story line.