A Murderous Wavelength (殺人の波長, Satsujin no Hachō), known as simply Bloodlust (血に飢える, Chiniueru) in the anime, is a wavelength type created from an individual's pent up anger. Only one person within the Soul Eater series has sported this type of wavelength.
As seen with Giriko, those with a Murderous Wavelength are invdividuals who've hidden a great amount of negative anger within them. Because of this, a murderous quality is shown within their wavelength, represented by a pink-hued rings around the individual (at least in weapon form) in the anime. With a murderous wavelength, an individual sanity, similar to that of a Madness Wavelength, is much less sound, though their anger may make their attacks more powerful.
However, there is an incredible drawback to those with this wavelength. Due to the strain the Murderous Wavelength puts on the soul, if the carrier is too angry and unstable, the soul will burst and kill the carrier instantly.