William McCastlin

I have been researching my Great Grandfather for many years, No one in the family has ever been able to confirm where he disappeared to. I have come across a bio here for him and am wondering how I can go about actually proving it is him. Any advice?
If you can't find much info on him you might try researching his wife and see if you can tie him in that way. If the bio of the person here is your great grandfather then she I assume would be your great grandmother. The bio here on E.T. says he was married to Agnes McClusky in 1906. Research her and see where it leads. Just a suggestion. Good Luck on your research.
Thank you. Agnes was my Great grandmother and she did marry William McCastlin in 1906 they had two sons William my Grandfather and Joseph(Perhaps a daughter Mary also but her parentage has always been debated). The problem is William McCastlin disappeared from our family and no one ever spoke of him. Many of us have been searching for him for many years. We knew he was a sailor. The discrepancy in his age on the records is what is throwing me off. Is there a way to see an image of the original showing the smudge or to see any records showing next of kin. If this is our William he deserves to be claimed.