It stands to reason that if she killed the moneylender because she was afraid her husband would leave her if he knew about her debt, that she would ask her 16-17 year old son/nephew for help moving the body before asking her husband. We know she asked him to get rid of the bike, or at least drive it away from her house.
Did the police find body parts in her freezer or were they all disposed of by then? I still don't get why she confessed. Even if the police suspected her, even if they had video of the moneylender arriving at her house and the son riding off with her bike, just keep your mouth shut.
Or say "She left in a tuk tuk and asked me to have my son drive her moto somewhere, and I don't know why the video doesn't show her leaving in a tuk tuk, it's fucking Cambodia nothing works here there are power outages every day." Then let the police try to convict her with no murder weapon, no confession, no known motive, etc.
Talking to the police is always dumb. Always.