Apple ID of deceased member of family deleted but devices are still locked

Did you follow the procedure in this support article? How to request access to a deceased family member’s Apple Account - Apple Support

If you did, contact Apple again.

If you did not and you simply requested Apple delete the account then you may have to try the standard activation lock request route. -->

Apple can completely reset a device if a person can provide sufficient evidence of valid ownership. Read the requirements and steps for an Activation Lock support request at: https://al-support.apple.com/#/additional-support and links at the bottom right for the type of service requested. Apple says they may require "proof of purchase documentation” and that you need “proof of ownership documentation”, but does not detail what currently constitutes proof other than it “must include the product serial number, IMEI or MEID.” User reports on this community indicate that typically Apple will ONLY accept an original receipt issued by Apple or an Apple Authorized Reseller. Presumably this is the only kind Apple can authenticate against fraud since Apple is not involved in third party sales. Apple recommends that you "Keep your receipt after you buy an Apple device" --> Keep your receipt after you buy an Apple device - Apple Support

I suspect you are dealing with different departments at Apple. (Remember that this is a user-to-user forum; none of us work for Apple and don't know their inner workings.) There may be the people who deal with issues of accounts of the deceased, and there's the activation lock people. It could be two different services with whom you have to deal with separately, and each according to their requirements. If you sent the death certificate to the unlocking service they may not have recognized what it was for, and it wouldn't act as proof of ownership.

If they are not recognizing a receipt from an official Apple authorized dealer then try contacting Apple about this.

Refer to this page for Apple Support features ➔ Contact - Official Apple Support

Select from the presented options until you find a solution for your issue, or see if there is a chat or phone call contact method offered lower on the page under “Get more help” (you sometimes have to narrow down the options multiple times before this is shown). If you do not see your issue, keep experimenting with any series of selections until you reach one that offers a chat session or a telephone call and get the representative to redirect you.

This support article has various country telephone numbers for contacting Apple for support and service ➔ Contact Apple Support - Apple Support For some countries look under “Other” listing at the end of the list. Not every country has telephone support, and phone numbers may only work when calling from the same country.

P.S. There is nothing anybody on this forum can do to directly help you with Apple, so we do not need to see any documentation. If you post anything, please make sure it does not contain personal information since this is a worldwide forum and personal information invites being added to spam lists. ;-)

Are they an Apple authorized retailer? If they are a third party retailer, Apple will not be able to verify the authenticity of the receipt.