See my previous post. You aren't correct. She had trismus as a result of her manner of death, NOT rigor mortis.
Think again. Instant onset rigor mortis:
Physical exertion just prior to death: If someone dies while engaged in strenuous activity like exercising or struggling against drowning, rigor mortis can set in immediately. This instant onset, sometimes called cadaveric spasm, happens because the person's muscles, at the moment of death, were depleted of oxygen energy and ATP. This is why the victim of a violent attack may still be clutching the attacker's hair or a piece of clothing.
http://health.howstuffworks.com/diseases-conditions/death-dying/rigor-mortis-cause2.htm