A native of Wisconsin, Knipfel, who suffers from retinitis pigmentosa, is the author of three memoirs, Slackjaw, Quitting the Nairobi Trio, and Ruining It for Everybody; as well as two novels, The Buzzing, and Noogie's Time to Shine.

He wrote news stories, film and music reviews, the crime blotter, and feature articles until June 13, 2006, for the weekly alternative newspaper New York Press.

He wrote of a failed attempt to steal the corpse of the notorious American killer and graverobber Ed Gein from the graveyard at the Mendota Mental Health Institute in Madison.

[11][12] The first draft of Slackjaw was completed in two weeks, and at 500 pages long it was largely a collection of several dozen independent stories drawn from his columns.

With this theme in mind, Knipfel rewrote several drafts of Slackjaw, "looking at the stories in a different way and trying to find something that flows and has a rhythm", which finally produced a leaner memoir of which 60% of the content was fresh.

A much-publicized blurb was provided by the reclusive novelist Thomas Pynchon, who received the galley proofs of this and subsequent works, describing Slackjaw as "an extraordinary emotional ride, through the lives and times of reader and writer alike, maniacally aglow with a born storyteller's gifts of observation".

[5] Roger K. Miller in The Chicago Sun-Times described Slackjaw as "a volume to set opposite all those chirpy, slurpy books on maximizing your potential, enhancing your self-esteem and accessing your inner powers" and Ellen Clegg in The Boston Globe summed it up succinctly as "a disease book with an attitude", elaborating that "Knipfel seems content to let the inner felon emerge.

In contrast to his first book tour, Knipfel remained in New York City to promote Quitting the Nairobi Trio, a chronicle of the six months he spent in a locked psychiatric ward in Minneapolis following his last suicide attempt.

[16][17] Ellen Clegg in The Boston Globe believed that while personal hallucinations are "important to the beholder [they] don't always translate in the wider world" and Daphne Merkin in The New York Times expressed how her interest flagged "only when [Knipfel] went into lengthy descriptions of his wearyingly vivid dreams".

[32] The Brooklyn blog Brownstoner wrote that Knipfel's "new rant about Park Slope stroller culture ... sets the bar high for future diatribes on the subject".

He has complained about excessive media coverage of Heath Ledger's death, wrote about Charlton Heston's obituary, and, for a number of years, has written an annual column on notable passings.