You’re right, DO may not have been entirely honest about the genealogy angle and it’s possible he whitewashed his story for another reason aside from a coverup from guilt. A child of a raging, domineering patent/father, can develop a tendency to not always be truthful - self-preservation, avoidance from unjust anger, blame and wrath, all that. DOs body language during that interrogation, as if he hoped his chair would swallow him up, left me with the impression of such a person carrying baggage due to a domineering parent.
Therefore if the office visits began with talk of genealogy but turned financial or verged to other realities such as the topic of his father’s affair with the realtor, etc which then led to harsh, angry words - if DO walked out the office door upset but his father still alive - DO may not fabricated a different story as he’d have surely known admittance to any type of confrontation would surely also insinuate his guilt of murder as well. During the interrogation the 2nd detective attempted to paint that same scenario a little too obviously I thought, as if he hoped it to become the ah-ha moment.
But it’s the prosecution who must prove guilt, the defendant isn’t required to prove their innocence. Lies alone do not prove one committed murder. I think the Judge was right in the Not Guilty verdict.