I found this chronicle on a PDF document called Hondas y boleadoras en la América hispana by Jesus Vega Hernandez (Hondero) the same guy who wrote "Historia de la honda"
Google the title and you´ll find it.

One interesting segment tells how Joan Pizarro got killed battling the Incan army. The sequence of events goes like this:

-The Spaniards and their native allies have the low ground. The Inca resistance has strategically placed defenses on the high ground. Slingers bombard the Spaniards with rocks.
-At some point in the battle, a Spanish soldier called Pedro del Barco takes a sling shot to the head. It is unclear whether he survived or not, it is mentioned he "fell down, knocked out cold"
-Joan Pizarro rushes to help the fallen soldier. He takes a sling shot to the jawbone. A wounded Joan Pizarro remains with the horsemen.  
-The next day, Joan Pizarro himself leads a new attack. Due to his wound, he is unable to wear a helmet, but carries a shield instead.
-At some point, he failed to cover his head with the shield. A sling shot hits him in the head.
-Joan Pizarro dies 2 weeks later.

Thanks for sharing the translation with us. An interesting history vignette.

I suppose it's the infection after the skull fracture that killed him ?

Thearos wrote on Dec 9^th, 2010 at 12:07pm:

I suppose it's the infection after the skull fracture that killed him ?

I'd put my money an a slow brain bleed. Pressure builds over time with the injured person looking acting and talking normally for the first day or so and then weird neuro- symptoms start popping up. One of the more noticeable early symptoms can be slurred speech, but the broken jaw would mask that. People with brain bleeds are often misdiagnosed with concussions, so it could have been mistreated up until Pizarro died.

http://latinamericanhistory.about.com/od/theconquistadors/p/09juanpizarro.htm

A biography of Joan Pizarro. I read somewhere that he "agonized for weeks". Also the chronicle says that the stone cracked his skull.