Those of you who think he turned himself in just because she gave him sincere parting words are ignoring that he had already outed his intent to commit a crime (hence the recording of his number and voice) and his bank account number. He must've been stupid enough to personally open that account, because having a decoy open one in your stead would've been easy to cut loose if compromised.
At that point, turning himself in was the only viable move left, to lessen the inevitable charges. If he tries to make a run for it and fails, kiss any plea deal goodbye.