Drugs Harm More Than the User

My niece's dad is in prison for a crime he committed while on drugs.  She has been without her dad for years, and will continue to be for a couple more years at least.  The crime he committed - he definitely deserved the time (and more in my opinion).  It makes me wonder though, if he'd had been sentenced to entering one of the detox centers for a rapid detox and then major rehab, before things got so bad, would he have ended up a felon?  How does an Engineer with a great job go from having what most people want to sharing a cell, leaving a little girl without her dad (and believe me, she feels the absence of her father badly).

He tried to kick his drug habit a few times but it never worked for him.  If he'd gone into a detox that lasted longer, with longer recovery and follow-up psychological counseling for at least a couple months, would he have been successful? 

I wonder if he's received the detox and rehab while in prison so when he gets out, he'll be able to stay clean and actually participate in raising his child.  I hope so.