Hi Vince! How's it going?
There is no easy answer to that question. I would say, however, that being a friend cuts both ways. I would hope that no friend of mine would put me in the position of having to lie for him---(Remember the finger-wagging Bill Clinton and the awkward position he put his administration loyalists in, concerning Monica Lewinsky?).
Also, what are we talking about: a death that may or may not be homicide? a death that may or may not have been accidental?
What if the police penetrate my lie? That might lead them to think of me as an "accessory"---at very least, what is it?, an "accessory-after-the-fact"?
The lie would have to be impenetrable. It would have to come from an unimpeachable source.
What about giving a "friend" an "alibi"?
One has to consider the idea that a criminal is trading on your "friendship" as cover for his crime(s); and that, perhaps, you never really knew him or her at all.
No easy answers, Vince. Sorry!