If the collector ascertains or has just cause to believe that any person is indebted to, or has in his possession or under his control any money, property, or choses in action belonging to any delinquent taxpayer in his county, he shall forthwith serve upon such person a notice in writing to appear before some court in the county having jurisdiction of the amount involved, naming the court, to answer as garnishee and under oath whether he was indebted to such taxpayer at the time of the service of the notice or at the time of making his answer, or whether he will be indebted to him by any contract then existing, and if so, the amount of such indebtedness, and whether he has in his possession, or under his control any and what money, property, or choses in action belonging to such taxpayer; and in such notice he shall state the amount of the taxes and fees due from such taxpayer. He shall also forthwith give such taxpayer, if in the county, written notice of the service of such garnishment; and if he is not in the county and resides in the state, and his address is known or can be ascertained, he shall give notice to such taxpayer, and the garnishment and notice he shall, without delay, return executed to the court before which the garnishee is cited to appear. It shall be the duty of the collector, as far as by diligent inquiry he can, to ascertain what persons are indebted to or have in their possession any money, property, or choses in action belonging to any delinquent taxpayer.