A hypothetical statistical analysis that doesn'tr capture reality.
The definition of "poor" can be engineered to produce whatever result you like.
A drugdealer who makes $500,000 a year in unreported tax-free income magically becomes "poor" when he is up on first-degree murder charges. Why? Because from a legally-reported income perspective he is an unemployed school dropout whose last legal address was in an impoverished neighborhood.
A truck driver who makes $35,000 a year in pre-tax income becomes "middle class" when he is up on first-degree murder charges.
Why? Because he is gainfully employed, pays taxes and lives in a respectable neighborhood.
The designation is almost completely arbitrary unless we are talking about the microscopic percentage of accused first-degree murderers who actually are independently wealthy.
In that case we are talking about 1 out of 100,000 and not 20 out of 100.