In People v Campbell (2011 NY Slip Op 00813 [4th Dept 2/11/11]) the Court held that it was error to summarily deny a motion pursuant to CPL 440.10, based on the contention that the defendant was denied effective assistance of counsel because his trial attorney had failed to inform him of potentially exculpatory evidence, i.e., that before the murder an inmate at a state prison had advised the District Attorney that he had information concerning a plot to murder the victim that implicated persons other than defendant.

The Court explained that a hearing on this motion was required where

It is undisputed that defendant's trial counsel had obtained an "open file" discovery arrangement with the District Attorney and that the correspondence was included in the file. Despite the fact that counsel representing defendant on the CPL 440.10 motion asked defendant's trial counsel to provide an affidavit setting forth what he knew and what he had advised defendant about the information in that correspondence, trial counsel failed to provide the affidavit..... We therefore conclude, based upon the record before us, that " a hearing should be held to promote justice [because] the issues raised by the motion are sufficiently unusual and suggest searching investigation' " (People v Ausserau, 77 AD2d 152, 155, quoting People v Crimmins, 38 NY2d 407, 416; see People v Kearney, 78 AD3d 1329; People v Nicholson, 222 AD2d 1055, 1057).