how would i know if he's dead?

Answers:
From the wording of your question, I'll assume you mean an absentee father, brother or other family member. There is no sure way, other than attending the funeral or seeing a death certificate, to determine if someone has died. People disappear all the time, assumed dead, until they turn up somewhere due to arrest, hospitalization or otherwise. If you are trying to track down a family member, a good starting point would be the Social Security office. Any activity on the person's SSN is recorded. But lack of activity on the SSN does not necessarily indicate death. People stop working, claiming taxes and change identities all the time. A perfect example is to go to any major city and look at the homeless population. A majority of these people will be considered "missing" until their deaths, when their identities can be determined. Until then, their family has no way of knowing whether or not they are dead.

Sorry my answer couldn't be more definitive. I just don't think theres any way to know for sure.

Other answers:
who? what dead???

who? what dead???

he wouldnt be breathing???

He's not moving or breathing.

is he a plant?????

Who and when?

He would start to stink up your house & the dog would be gnawing on mysterious appendages.

check his pulse and breathing.

Just curious, but who are we talking about?

who or what are we talking about here?
Jesus?...Family pet?...Dad?...Mom?...Uncle Tom?

If he ain't breathing, he is dead.

Call 911, if you can find the number.

If his heart is not beating, he is dead.