Lividity and Rigor Mortis: Determining The Time Of Death

Determining The Time of Death

When the heart stops beating, gravity pulls blood to the lowest point in the body. Blood pooling in those low areas stain the surrounding tissue giving the appearance of bruising. This staining of tissue is called livor mortis, or lividity. For example, a victim lying flat on his back when he dies exhibits lividity on his back, buttocks, and the back of his legs. The same is true on the front of the body, if the victim is found lying face down.

Livor Mortis (lividity) can help investigators determine the time of death. The staining of tissue normally begins within the first two hours after death. The process reaches it’s full peak in eight to twelve hours.

If the victim is moved during the first six hours after death the purplish discoloration can shift, causing the new, lowest portion of the body to exhibit lividity.

After a period of six to eight hours after death, lividity becomes totally fixed. Moving the body after eight hours will not change the patterns of discoloration. Therefore, investigators know a body found lying face down with lividity on the back, has been moved.

Rookie officers have often confused lividity with bruising caused by fighting.

Remember, ambient air temperature is always a factor in determining the TOD (time of death). A hot climate can accelerate lividity, while a colder air temperature can slow it down considerably.

Rigor Mortis is the stiffening of muscles after death. The muscle stiffening (hence the use of the term, stiff) is caused by the loss of adenosine triphosphate (ATP) from the muscle tissue. Without ATP, the muscles can no longer function normally, and begin to contract and stiffen.

Rigor mortis begins in the smaller muscles of the face and neck in about two hours after death. The process then moves downward from the head to the feet. The body becomes completely stiff in approximately eight to twelve hours.

Bodies remain rigid (the rigid stage of rigor mortis) for approximately eighteen hours, at which time the process begins to reverse itself in the exact same order – small muscles first, followed by the larger ones, moving from head to toe.

In approximately twelve hours the body returns to a flaccid state.

Again, like livor mortis, air temperature is a factor that can accelerate or slow down rigor mortis. Certain poisons and illnesses can also affect rigor mortis.

Determing TOD using rigor mortis is not an exact science.

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10 replies
  1. Auntieamy71
    Auntieamy71 says:

    Lee,

    Don’t worry about the naysayers, they’re just jealous! Stuff happens. I love this site! As for the dog….*hee*

    I have a friend whose father would say when the cat was in that position, he would say that is was ‘rigor meowtis’

  2. D. Swords
    D. Swords says:

    Well, I don’t know who said what, but three cheers for the Graveyard Shift.

    Hip Hip Hooray! (repeat twice)

    It’s a lot of fun, and very informative.

  3. Elena
    Elena says:

    Glad I missed whatever I missed and hope it doesn’t happen again. This blog is too much fun – opps – “professionally interesting” to allow it to lose in any way.

    Loved the dog – have an evil black cat who does the same thing in the hopes that someone will be transfixed by the tempting belly and forget the five lethal weapons residing on each of four feet !

  4. Terry
    Terry says:

    Gee, I got busy and missed all the dirt. This is a fantastic place, and it’s all about the content. Anyone who complains — well, give them their money back.

  8. seanachi
    seanachi says:

    Lee,

    Ignore the nitpicky naysayers. The rest of us really appreciate all the time and effort you put into providing us with informative and interesting posts. So I for one say a great big THANK YOU!

  9. Terri Thayer
    Terri Thayer says:

    Lee,

    Don’t let the turkeys get you down.

    This blog is a wonderful resource. To have this kind of information, literally at our fingertips, is amazing. And it’s free! I marvel every day at the depth of knowledge of you and your experts and the generosity involved.

    Anyone who writes knows it’s not easy to do this day after day. It’s insane that people are giving you shit about it.

    I never considered myself a part of the silent majority, but when it comes to the internet, I am just that. Just know there are plenty of us out here who appreciate what you’re doing.

  10. Wilfred Bereswill
    Wilfred Bereswill says:

    Lee, you’ll never get a complaint from me, but I know the feeling. I wrote a guest blog about using Microsoft Word as a word processor rather than a typewriter. Rather than a commentor focusing on the Word tips, she decided to critisize my prose (something to do with a dangling participle or something), throwing off the entire point of the article.

    Since I use WordPress on my blog, I know how difficult it is.

    Lee, just know that some of us appreciate the info and keep it up.

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