You issued cheques that weren't worth the paper they're written on. Landlord takes NSF cheques to police, files a police report BINGO you are now on a list to be detained and arrested should you ever pass through Doha (because you committed a crime, fraudulently writing cheques you were not prepared to pay) and possibly any other GCC country - pray you're never on a plane that's diverted to a GCC country because of mechanical or weather problems because you have created a more serious problem for yourself.

@snessy - they didn't default, they kept paying so no case could be filed. The OP left and emptied their accout so their cheques were returned for non sufficient funds which is illegal in Qatar without a police letter supporting such action