Received a check..not sure if its real...help please?

so my boyfriend got a check in the mail today..the envelope says its from davis smith with a return address from illinois..the check is made out to my boyfriend's full name and its for 2,950.00 the signature on the check is different from the name on the return address..the bank on the check is first national bank of omaha and is legit as i looked it up..and the business listed on the check is td ameritrade which is legit as i looked it up as well..we have called the police about it and they said they would come over but its been over and hour and still no sign of them..the weird thing is..is that the writing on the envelope is the same as my ex husband's writing..i called him thinking maybe he was pulling what he though a prank but he said he didnt..if he did..and i could prove it by matching the writing couldn't he get into trouble? even if he lives in a nother state? another weird thing is..that the check was written out to my boyfriend and the envelope isnt like a professional envelope.. the check wasnt typed or printed on someone wrote everything on it..i kinda think it was my ex just messing with him..idk how he could have done it..but i even showed my boyfriend and his friend the writing from him and compared it to the writing on the envelope[the writing on the check is different] and they said it was the same too..or very very similar..the check's memo says for travel expenses..so if i have already called the police who havent done anything..what do i do now? do you think its fake? or sounds like it could be real?? if my ex didnt write on the check itself but on the envelope and it was him could he get into trouble?? just curious thanks