Police make arrest in 15-year-old homicide case

By Mary Manning, Jinae West

Published Tuesday, June 16, 2009 | 11:56 a.m.

Updated Tuesday, June 16, 2009 | 6:57 p.m.

Metro Police announced today the arrest of a man in a 15-year-old unsolved homicide case in which a 7-year-old girl was sexually assaulted and suffocated to death.

Police arrested and charged 36-year-old Greg Wallen Jr. with one count of murder and one count of sexual assault with a victim under 14 years old, according to Clark County Detention Center records. No bail has been set.

He is a suspect in the death and sexual assault of Diana Hernandez, who disappeared on April 2, 1994, after a shopping trip with her mother and her siblings, while her mother stopped in the office of her apartment complex to pay rent.

Lt. Lew Roberts said Wallen was taken into custody Monday evening with help "from some very tenacious cold case detectives" and advances in forensic science, specifically in identifying DNA. Roberts said police were able to make a positive match to Wallen from samples found at the crime scene.

Diana was nearing her 8th birthday at the time of her death, Roberts said.

A review of the cold case had begun in January when family members and witnesses were re-interviewed, a police report indicated.

Detectives also reviewed evidence taken from the Sandpiper Apartment complex, 3955 Algonquin Ave., near Flamingo Road and Maryland Parkway, where Diana lived.

A day after her disappearance, police found Diana’s nude body in a box tossed into one of the apartment's trash bins. She had been sexually assaulted and suffocated.

Roberts said the case was revived because of new technologies available. Those advances brought to light more information about Wallen.

Roberts said Wallen didn’t have a serious criminal history until after 1994 and wasn’t considered a suspect at the time of Diana's death. Wallen was highlighted as a suspect only after police combed through old case files and looked into his history, Roberts said.

New information that raised questions about Wallen includes that he was convicted on sexual assault charges after Diana’s murder and is now a registered sex offender, which he wasn’t at the time of her death, police said.

Roberts confirmed that Wallen lived in the same complex as Diana and assisted her mother in search efforts with other residents after the girl’s disappearance.

As part of the cold case investigation, detectives reviewed a list of people living at the Sandpiper Apartment complex at the time of the murder and found that Wallen had a unit there, in the same building as Diana and her family.

Police compared Wallen's DNA with samples taken from Diana's body and used a partial fingerprint found on the outside of the box where her body had been found. The DNA samples from the girl's body matched Wallen's, police learned.

Roberts said because of advancements in DNA testing, other cold cases like Diana's have greater potential to be solved. He said he doesn’t know of any other potential victims of Wallen but urged anyone with information to contact Metro’s homicide bureau.