Does trial counsel have an obligation to conduct a meaningful and comprehensive voir dire as it relates to racial bias, explicit or implicit, of jurors

QUESTION PRESENTED 1) Does trial counsel have an obligation to conduct a meaningful and comprehensive voir dire as it relates to racial bias, explicit or implicit, of jurors whose responses on their juror questionnaires indicate the presence of a racial bias against the Defendant and where those jurors were selected as members of the panel who would ultimately vote in favor of a death sentence? 2) Where defense counsel abdicates its constitutional duties to voir dire prospective jurors as it relates to racial bias, explicit or implicit, and where the trial court fails to assure the empaneling of an unbiased jury, is structural error present? i