'Fade to black' is your friend - as is 'graphic details not required'.
Here's a taste of what I'm talking about. Nip is an incredibly important person in the main character's life. He's the one who taught her how to use her magic, and has been a dear friend and mentor to her. This takes place near the very end of the second story, and Nip is in his late 90's at this point. (Note: He's a human cat shaman)
WARNING: GRAPHIC
[spoiler]Nip sat at his desk, perusing over an old tome Ehran had permitted him to borrow. He suddenly felt a dark presence behind him. He closed the tome and sat back in his overstuffed chair.
"I know who you are, and why you are here." He spoke calmly, and leaned his head back. "Go ahead. I'm an old man, and I am ready to die."
Vestrial produced a vicious looking dagger from under his black cloak and stepped forward, his mouth twisted in a cruel grin. He held Nip's chin gently, and plunged his blade into the old shaman's chest. Nip let out an involuntary gasp as the air was forced from his lungs.
"Your beloved student defied me. You will suffer greatly for her arrogance." The mad passion hissed.
Nip's body went limp, and the blood red gem on the pommel of the dagger flashed. The roman numeral tattoo on his forearm changed from VII to VI. Nip's body twitched and blood spewed from his mouth before going limp once more. The gem flashed again.
V
Again his body twitched, and again the gem flashed.
IV
Nip's eyes flickered open and stared up at Vestrial in fear and pain, then stared into nothingness. The gem flashed.
III
He blinked, and emitted a gargled moan. The gem flashed.
II
Blood sprayed from his mouth and across the desk as his body spasmed once more. The gem flashed.
I
Nip's jaw went lax, and his eyes dulled. The gem flashed one last time, and the tattoo faded away.[/spoiler]