Ever wonder what happens to the cast-off T-shirts worn by prisoners?

No, we didn’t either.

Until we heard about Raquel Allegra. The L.A.-based designer gathers worn-out jailbird white Ts by the ton and then magically turns them into delicate, sheer pieces of clothing/art.

Her designs are amazing transformations: she distresses, stretches, cuts, makes sheer, rips and creates spider-webby looks out of the L.A. County Jail rejects to make everything from tops to dresses to men’s shirts to scarves.

She’s no secret in California: Celebs such as Heidi Klum, Penelope Cruz and Mary Kate Olsen have worn her designs. Allegra’s Web site features her spring collection, which in no way resembles anything even remotely related to a jail.

Examples: a pleated and draped, asymmetrically hemmed dress (above left), a sheer taupe caftan that wafts down the runway with a delicate brown graphic print on it (above right), and an almost-evening-wear black dress is short in front and sheer and long in the back, almost like a train (above left).

There is only one online source to buy Allegra items, Shopflick.com. The site provides lots of information about Allegra and how she makes her creations, down to a video that shows her step-by-step process (Allegra, above, sifts through a new shipment of prison Ts).

Alas, the convict-born creations don’t come cheap: a shredded tank is $198, a long and lavish scarf (below left) is $590 and a shredded caftan (below right) is $1,190. But they’re all one of a kind.

And you don’t need to spend more than a few minutes thinking about the crime commited by the last person who wore your delicate new purchase.