Dear Family Member Name,
I am so sorry to hear the sad news about John and wish to offer you and your family my sincerest sympathy. I worked with John for many years and in addition to being a valued colleague, he was a dear friend.
John was a tremendous asset to our office and the entire staff had a great admiration and respect for his work and his accomplishments for our company.
If there is anything at all I can do to help during this very difficult time, please do not hesitate to contact me. I'm available via phone (111-111-1111) or email at firstname.lastname@example.org.
With my deepest sympathy,
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