ASM disks dropped - is all the data erased from the disks

Hello,

 

We recently moved to new LUNs and added the new disks to our ASM diskgroups, we then dropped the old disks. This is a production environment (11gr2 on Red Hat Linux 6.5) and the data is highly confidential, is there a way to verify all the data has been completely erased from the dropped disks. Did the asm drop disk process remove all data from the disks. The dropped disks show as former disks with used space as zero, but business needs to know for certain if all data has been wiped from the disks.

 

Please provide ways of confirming that the disks are now clean and can be removed from OS level.