It can be regarded as the crime of fraud, and the qualitative key of fraud lies in the motive and means of the criminal suspect to ask for property. Since he has no ability to perform the contract, but for the purpose of illegal possession, it can completely constitute the crime of fraud.

He's behavior in this case belongs to the act of fabricating facts, concealing the truth, defrauding the victim's trust and demanding property from the victim for the purpose of illegal possession. Writing an IOU to the victim afterwards does not affect the determination of fraud.

It is recommended to report the case to the public security organ. Generally speaking, public security organs are relatively cautious in filing cases, and the behavior review of such IOUs will be more stringent. Therefore, it is necessary to collect relevant evidence to prove that the suspect does not have the ability to perform the contract, but gains the trust of the victim through deception. You'd better consult a lawyer.