Hello and welcome to the Apple Support Communities in Portuguese.
My feelings about this situation. I hope that you're having the best assistance at this moment.
To get your old iPhone IMEI you can check it on Apple ID website. On this website click on Devices tab and search for your lost or stolen device. If available the IMEI will be showed bellow the iPhone information.
Notice that your device needs to be logged in your account to be found in this website. If it's not logged in, you can search for IMEI in the original packaging. More information are available here -> Find the serial number or IMEI on your iPhone, iPad, or iPod touch - Apple Support.
Is very welcome to follow all the guidance of the police in situations like that. Please be safe and well.
Best regards. :)