Unless a guardian shall have been appointed by a court of competent jurisdiction, the Department of Health and Human Services shall take custody of and exercise general control over assets owned by children under the charge of the department. Children owning assets shall at all times pay for personal items. Assets over and above a maximum of one thousand dollars and current income shall be available for reimbursement to the state for the cost of care. Assets may be deposited in a checking account, invested in United States bonds, or deposited in a savings account insured by the United States Government. All income received from the investment or deposit of assets shall be credited to the individual child whose assets were invested or deposited. The department shall make and maintain detailed records showing all receipts, investments, and expenditures of assets owned by children under the charge of the department.