My mom's boyfriend of 20 years has took over my mom's body when she died. How do her children deal with this?

he tells us that he had her cremated we have no proof of this.He didnt even call and let the children know she had passed away untill a week after she died,we believe this was a plan not to let anyone know untill he got all her belongings out of her house so that the children wouldnt be over there going thru her stuff taking what they want.He also told us he had her cremated at her wish!dont even know what furneral home she was cremated at,he wont give us any information.Also he says she didnt want it put in the obituaries cause she didnt want anyone to know she died..He said she gave him a list that he would get to later.He is being very evasive.Is all this even legal?we dont even know where our mother is at,or who has her,he says it takes awhile to get the ashes back,maybe he does have the power to carry out her wishes like this,but we wouldnt know,we have never seen any paper work saying he does.My mother had alot of valuable things,couple cars,a very large expensive doll collections,large amount of jewlery,but most of all our family pictures,he has took everything out of her house.we need help!