Little reportedly told officers that he was a good drawer and promised a year ago to produce portraits of his victims from memory.
One of the sketches is of a black woman whom Little claims to have killed in 1976 or 1977 in Wichita Falls. The FBI hopes that by releasing the images and details, local law enforcement agencies or the general public may be able to make a link between a woman who went missing at the time or a Jane Doe body that was found-and ultimately provide some closure for the families of the victims.
So far investigators have managed to link Little to 36 of his claims, spanning the width of the USA, from LA to Washington DC.
The strategy has worked before, Buchwald said.
She added that Little's recollections and drawings have been strikingly accurate; two of his drawings have already helped investigators match his accounts to cold cases.
Little, a 1.9m former boxer also known as Samuel McDowell, is serving a life sentence for murder in a Texas prison.
Samuel Little, 78, has confessed to 90 sex slayings between 1970 and 2005 in a blood-soaked odyssey that stretched from the Gulf of Mexico to Cleveland, to Los Angeles, Miami and all points in between.
Besides drawing what the women looked like, he also remembered what auto he was driving, where he killed them and how he did it.
Visit the FBI's website to see more information about each of Little's portraits, including when and where each alleged victim may have been killed.More news: All-Star game marks latest milestone for Michael Jordan
More news: The end has finally come for NASA's Opportunity Mars rover
More news: Former US air force officer charged with spying for Iran
He mainly targeted drug addicts and prostitutes during his decades-long coast-to-coast murder spree, and many of his victims were never identified.
Then in 2014, Little was sentenced to three consecutive terms of life in prison without parole for the beating and strangulation murders of Carol Alford, 41, Audrey Nelson, 35, and 46-year-old Guadalupe Apodaca.
"Over the course of that interview in May, he went through city and state and gave Ranger Holland the number of people he killed in each place", said Federal Bureau of Investigation analyst Christie Palazzolo. "Jackson, Mississippi - one; Cincinnati, Ohio - one; Phoenix, Arizona - three; Las Vegas, Nevada - one".
A murder in Odessa, Texas, fit the bill and Little developed a trust with Texas Ranger James Holland and spilled his guts.
Investigators have confirmed 34 of the confessed killings, authorities said in November.
However, more than half of his confessions are yet to be confirmed or matched to open cases.
This undated file photo provided by the Ector County Texas Sheriff's Office shows Samuel Little.
CNN has reached out to E.J. Leach, the attorney representing Little in the Texas case, and has not yet received a response.