I lived and worked in Saudi for the whole year but my 10 y/o lived in the states with my sister whom I paid 12k a year to take care of her. I am unmarried. I do have a checking account and savings account in the states. I am a US citizen.

You would owe MD income taxes if you either lived in or worked in MD. If you were out of state all year then you can argue that you did neither. I assume you do not own a house in MD - is that correct? The definition of "resident" on the MD website does not apply to you, since you were not domiciled in MD nor present in the state for at last 6 months - see: Maryland Filing Information - Filing Information for Residents

No I don't currently own any house in the state but I do own a car that's parked in my sisters driveway that I make payments on although the tags were turned in before I left for KSA. I also hold a drivers license that is not yet expired with my sisters address and vote using an absentee ballot. I heard that these things can signal my intent to return to the state and therefore qualify me as a resident obligated to pay MD state tax. Is this in anyway true?