DALLAS (CBSDFW.COM/AP) — Over the years an admitted serial killer being held in Texas has drawn pictures of some of his victims and now the FBI has released those sketches.

The Bureau has also released additional information on a string of unsolved cold-case homicides to which investigators say Samuel Little has confessed.

The FBI updated a post made on its website in November. The fresh information included drawings made recently by Little, based on his memories of some of his victims.

(credit: Marion County [Florida] Sheriff’s Office)

An FBI statement says Little targeted “marginalized and vulnerable women who were often involved in prostitution and addicted to drugs.” The bureau hopes the information will generate tips and clues from the public that could help solve the dozens of unsolved homicides.

According to the Texas Rangers, Little has confessed to 90 murders to date. They include women in Texas and across the country and happened over the past four decades.

Initially Little, who had been convicted of three murders in California, was extradited from to Wise County, Texas where he was believed to have committed a murder. Officials there later determined he had no connection to their case and sent him to Ector County, in Odessa, where he was ultimately convicted of murdering Denise Christie Brothers in 1994.

The FBI says Little, who’s 78 and bound by , is in poor health but is expected to remain in the Ector County Detention Center.

Woman (L) killed in Houston between 1976 and 1979 or in 1993. Woman (R) killed in Wichita Falls in 1976 or 1977. (credit: FBI)

Of the 16 drawings released this week, two of the victims are in Texas. The body of one woman, a Black female killed in 1976 or 1977, was disposed of somewhere outside of the Wichita Falls city limits. The other victim, a Black female between 25 and 28 years old, was killed between 1976 and 1979 or in 1993 in Houston.

Ector County District Attorney Bobby Bland said 50 cold homicide cases have been closed as a result and most of the unsolved homicides remaining are in California.

The FBI says Little, whom the bureau said “may be among the most prolific serial killers in U.S. history,” has a criminal record dating to 1956. But only recently has he opened up about the long list of killings he has said he committed.

Agents who have interviewed Little, a former boxer, say he remembers his victims and the killings in great detail, including where he was and what car he was driving. But he could provide little help on dates, creating a challenge that the FBI hopes Little’s drawings can help surmount.

(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)