“The Mind of Mark DeFriest” uses animated sequences to portray some of its subject’s exploits. (Found Object Films/Nakedge Films)

Less than 15 minutes into the “The Mind of Mark DeFriest,” the subject of this documentary — a prisoner in shackles — turns to the camera and asks, with a laugh, “Do I seem crazy? Can we have an honest opinion from the peanut gallery?”

Don’t answer that question.

At least not yet. As you watch the rest of Gabriel London’s compelling film unfold, your opinion about the sanity of its titular subject may change, more than once. In 1980, at the age of 20, DeFriest was sent to a Florida prison for the theft of some tools. That four-year sentence ultimately stretched to 105 years after repeated escape attempts and other erratic, less-than-model behavior that raised questions about his competency.

The opinion of psychologist Robert Berland — who, early in DeFriest’s sentence, testified that the prisoner was faking signs of mental illness — has certainly changed. London’s film centers on the efforts of Berland, who, along with DeFriest’s wife and lawyer, has been trying in recent years to get the Florida parole board to recognize that Berland’s earlier expert opinion was in error, and that DeFriest is — indeed, that he probably always was — psychotic.

This makes for a dramatic tale. But so do De­Friest’s firsthand accounts of his seven escapes (out of 13 attempts), which show why he was dubbed “Houdini” by the press. DeFriest provides lively interviews, some of which are unfortunately garbled by bad phone connections. London supplements these with animated reenactments of his exploits, sometimes narrated by actor Scoot McNairy, who reads from DeFriest’s journals, letters and court transcripts. This prisoner comes across as someone with great native intelligence, if not always the best judgment.

Of course, cleverness, as several people interviewed for the film note, is not the same as sanity.

After an earlier version of the film was shown at film festivals last year, late-breaking developments in DeFriest’s case forced London to update the movie, which now includes something of a surprise ending.

But the biggest surprise may be the way London turns the portrait of an escape artist into a powerful indictment of the American prison system, which many reformers, London included, argue merely warehouses the mentally ill.

Unrated. At the West End Cinema. Contains obscenity, sexual content, drug references and brief violent imagery. 92 minutes.