How does L deduce that Kira needs a name and not just a face?


This is something that I've been wondering about, how does L deduce that Kira
needs a name? Surely all the victims he investigated had their name and face,
but how can he figure that he needs both? The stunt on tv with Lind L. Tailor
only proved that Kira can't kill anyone, and there are certain criteria. I'm
not sure how that concludes that he needs both name and face.

Edit: To clarify, here's how I look at it. L analyzes all the victims of the
Kira killings and noticed that what was broadcast about the criminals was
their face and their name. How does he conclude that Kira needs both? Why not
just a face? When Kira kills Lind L. Tailor, that only validates that Kira has
the ability to kill people, to which L himself even says "I couldn't believe
it until I saw it, but it appears you can kill without being there in person."
When Kira subsequently is unable to kill L, L can then deduce that there are
people Kira can't kill. However he concludes Kira needs both name and face,
which I don't understand. To me, at that point 3 conclusions are viable: Kira
needs a name AND a face. Kira needs just a name. Kira needs just a face.




Just reread the manga and it turn out it was the police, probably with L help,
that concluded the fact that Kira need both name and face

from Death Note Chapter 11 One, page 5

> Matsuda: He needs to know names? Is that true? I've heard he only needs to
> know the face
>
> Chief Yagami: Criminals whose names were either wrong or kept hidden
> survived some mass killings, so the headquarters came to that conclusion

[![Death Note Chapter
11](https://i.stack.imgur.com/CDcdK.jpg)](https://i.stack.imgur.com/CDcdK.jpg)

L didn't do the stunt on tv with Lind L. Tailor to prove that Kira needs both
name and face. But rather to prove that Kira exist, can kill people without
being nearby, and live in Kanto area in Japan.

