This Thursday and Friday, April 5 and 6, will be your last chances to see the Isley Brothers (all two of them) for at least three years—if not forever—when they perform at the Star Plaza. Singer Ronald Isley (aka Mr. Biggs) was sentenced to 37 months in prison for tax evasion back in September, a term he’ll begin serving once this tour wraps up. Considering his age (67) and health problems (he’s already had kidney cancer and a stroke), there’s no telling what kind of shape he’ll be in when he’s released.

Isley’s been a bit slippery with his finances for years now. In 1997 he declared bankruptcy after the IRS seized many of his assets, including cars and a yacht, and in 2002 he didn’t even both signing his tax return. Fortunately, he’s taken much better care of his career. Few groups have managed to be a force in pop music for as long as the Isleys. Their discography includes early rock ‘n’ roll (“Twist and Shout”), Motown (“This Old Heart of Mine”), psychedelic soul (“That Lady”), and seminal slow jams (“Don’t Say Goodnight”).

For more than a decade the group has been just Ronald and Ernie, whose fuzzy, flanged-out guitar-purr (the psychedelia of Hendrix transplanted to the boudoir) is just as distinctive as his brother’s silken, creamy croon. Their most recent album, the unfortunately titled Baby Makin’ Music (Def Soul), is fairly generic, suffering from unmemorable tunes and bland production, but Body Kiss (Dreamworks), which came out in 2003, remains a favorite of mine. Produced by R. Kelly, who also wrote all but one of its dozen tunes, it brilliantly showed how the Isley Brothers sound could survive in all climates. Some of the songs have ridiculous lyrics, including the otherwise gorgeous “Lucky Charm” (“Girl, you’re magically delicious”), but that only brings an added layer of pleasure.

The Isley’s current tour features a career-spanning set list that caters both to the oldies circuit and young slow-jam fans, though I’ve gotta say, Ronald whispering sweet nothings to girls five decades his junior is almost as bad as R. Kelly’s alleged indiscretions.