If Lindsay Lohan is sentenced to jail next month, she WILL do time behind bars -- this according to L.A. County Sheriff Lee Baca.
Baca just told FOX 11's Good Day L.A. ... the overcrowding problem will not keep Lindsay out of jail. Lindsay, he says, is a "sick" drug addict who needs jail to beat her demons -- and if the judge decides to sentence Lindsay for a probation violation, he'll make damn sure she serves time.
According to Baca, Lindsay needs at least 60 days in the slammer to be properly rehabilitated.
Judge Stephanie Sautner made a comment on the bench yesterday, suggesting that sentencing Lindsay to jail was futile because it's become a revolving door. But Baca is now giving her assurance to the contrary.