Police have released a composite sketch of a suspect wanted in connection with a series of rapes and a murder more than 20 years ago in Rockville, Maryland. Police were able to use the suspect's DNA to build the composite sketch.

WASHINGTON — Detectives with the Montgomery County Police Department’s Cold Case Squad released a composite sketch of a suspect wanted in a series of the rapes and a murder that happened more than 20 years.

Police said in a news release they were able to build the sketch from DNA the suspect left at the crime scenes.

The process is called DNA phenotyping, which predicts the physical appearance and ancestry from unidentified DNA. Parabon NanoLabs, a DNA technology company in Virginia that specializes in DNA phenotyping, produced the sketches that is referred to as a Snapshot composite.

The Snapshot used to the suspect’s DNA to produce trait predictions for the suspect’s ancestry, eye color, hair color, skin color, freckling and face shape. By combining these traits, the Snapshot composites were produced to show what the suspect might look like at a certain age and with a certain body mass index.

Detectives used default ages and default BMIs because age and BMI cannot be determined from DNA.

Police believe the suspect was involved the assault of three women, two of whom were raped and one was murdered.

The first incident happened on June 25, 1989, in Rockville, Maryland. Police said the victim, a 52-year-old woman, was walking on Lewis Avenue when the suspect approached her from behind, assaulted and then raped her. Police were able to recover DNA from the suspect in this case.

The second incident occurred five years later on Sept. 19, 1994.

Police said a 25-year-old victim was walking on Twinbrook Parkway when the suspect approached her from behind while armed with a knife. The suspect grabbed the victim and dragged her to the side of her residence where he attempted to rape her. The victim was able to resist the assault and flee to call police. No DNA evidence was collected in this incident.

The third incident happened on Oct. 3, 1994, when police found the body of 42-year-old Le Bich-Thuy to the side of her home in the 1600 block of Martha Terrace in Rockville.

Police said their investigation revealed that Le Bich-Thuy had been assaulted, raped and then strangled. DNA was recovered from this incident as well. Police were also able to determine the victim was last known to be alive at 10 p.m. when she left the Twinbrook Metro station in Rockville.

A DNA analysis determined that the suspect in the 1989 assault and rape had committed the 1994 rape and murder of Le Bich-Thuy.

Police are releasing the sketch with the hope that someone might recognize the suspect and be able to provide some information to police, but police caution this Snapshot might not necessarily be exactly how the suspect looks.

“It is important to note that Snapshot composites are scientific approximations of appearance based on DNA and are not likely to be exact replicas of appearance,” Montgomery County police said in a news release.

“Environmental factors such as smoking, drinking, diet, and other non-enviornmental factors — e.g., facial hair, hairstyle, scars, etc. — cannot be predicted by DNA analysis.”

Anyone who has information regarding the suspect or anyone who has details that might help investigators is asked to call the Major Crimes Division at 240-773-5070.