Interviewer: What is your father's name?
Interviewee: His name was John Doe.
Interviewer: So sorry. May I know what year he died in?

Is this necessary to use past tense in mentioning of the name of a person who has died? In the following sentence I have used is instead of was. Though F.S. Key has died long ago, he IS still the author of The Star-Spangled Banner.

The name of the author who wrote The Star-Spangled Banner is Francis Scott Key.

Likewise, in the above sentence, where interviewee said, His name was John Doe, couldn't he say, His name is John Doe? Because John Doe is still his father no matter even he is dead now.
Hi Jackson

When referring to the names of dead family members or other people with whom you had some kind of personal relationship, it is normal to use the past tense. Using the present tense suggests that such people are still alive and/or that the personal relationship is still current.

As a further example, if someone said "The name of my boss at ABC Company is John Smith", I would interpret that to mean not only that John Smith is still alive, but also that the person currently works at ABC Company. If someone said "The name of my boss at ABC Company was John Smith", my first interpretation would be that the person no longer works at that company. In other words, the person's business relationship with John Smith has ended.
Thank you, Amy.