Yes Smelly, it's true. If you google 'guilty plea' and look under 'news' you will see many murder cases that resulted in a guilty plea. Below I have a link to some stats from US Department of Justice.
Bureau of Justice Statistics
http://bjs.ojp.usdoj.gov/content/pub/pdf/dccc.pdf
Here is another one for you
About 60% of defendants were convicted of a felony
Sixty-eight percent of cases adjudicated within one year
resulted in a conviction. Fifty-nine percent of defendants
were convicted of a felony, and 9% of a misdemeanor.
The felony conviction rate was highest for those originally
charged with motor vehicle theft (74%), followed by drivingrelated offenses (73%), murder (70%), burglary (69%), and
drug trafficking (67%). Defendants charged with assault
(45%) had the lowest felony conviction rate.
Nearly all (97%) convictions obtained during the 1-year
study period were the result of a guilty plea. Eighty-seven
percent of guilty pleas were to a felony.
Seventy-nine percent of trials resulted in a guilty verdict or
judgment, including 82% of bench trials and 76% of jury
trials.
http://bjs.ojp.usdoj.gov/content/pub/pdf/fdluc04.pdf