Sex Crimes

Police say they will announce developments in 1975 case of sisters missing from Maryland mall

  • FILE - This file handout image provided by the Montgomery County, Md., Police Department shows photos from the original missing person/suspicious circumstances bulletin for the 1975 disappearance of two sisters in Maryland, Sheila Lyon and Katherine Lyon, who never returned home from a shopping mall. Police and prosecutors from Montgomery County, Maryland, and Bedford County, Virginia, will hold a news conference Wednesday, July 15, 2015, in Wheaton, Md., to announce what they call "significant developments" in the 40-year-old case.  (AP Photo/Montgomery County, Md., Police Department)

    FILE - This file handout image provided by the Montgomery County, Md., Police Department shows photos from the original missing person/suspicious circumstances bulletin for the 1975 disappearance of two sisters in Maryland, Sheila Lyon and Katherine Lyon, who never returned home from a shopping mall. Police and prosecutors from Montgomery County, Maryland, and Bedford County, Virginia, will hold a news conference Wednesday, July 15, 2015, in Wheaton, Md., to announce what they call "significant developments" in the 40-year-old case. (AP Photo/Montgomery County, Md., Police Department)  (The Associated Press)

  • John and Mary Lyon, parents of  missing sisters Katherine and Shelia, listen during a news conference in Wheaton, Md., Wednesday, July 15, 2015, on developments in the investigation of the disappearance of 10-year-old Katherine Lyon and 12-year-old Shelia Lyon in 1975. Authorities on Wednesday announced first-degree murder charges against an imprisoned sex offender in the disappearance of two sisters from a suburban Maryland mall in 1975, bringing some clarity to the baffling case that made parents question whether to allow children out of their homes alone.  (AP Photo/Molly Riley)

    John and Mary Lyon, parents of missing sisters Katherine and Shelia, listen during a news conference in Wheaton, Md., Wednesday, July 15, 2015, on developments in the investigation of the disappearance of 10-year-old Katherine Lyon and 12-year-old Shelia Lyon in 1975. Authorities on Wednesday announced first-degree murder charges against an imprisoned sex offender in the disappearance of two sisters from a suburban Maryland mall in 1975, bringing some clarity to the baffling case that made parents question whether to allow children out of their homes alone. (AP Photo/Molly Riley)  (The Associated Press)

  • Bedford County, Va. Sheriff Mike Brown speaks at a news conference with Commonwealth Attorney Randy Krantz, second left, to discuss developments in the investigation of the disappearance of 10-year-old Katherine Lyon and 12-year-old Shelia Lyon in 1975. Wednesday, July 15, 2015, in Wheaton, Md. Authorities on Wednesday announced first-degree murder charges against an imprisoned sex offender in the disappearance of two sisters from a suburban Maryland mall in 1975, bringing some clarity to the baffling case that made parents question whether to allow children out of their homes alone.  (AP Photo/Molly Riley)

    Bedford County, Va. Sheriff Mike Brown speaks at a news conference with Commonwealth Attorney Randy Krantz, second left, to discuss developments in the investigation of the disappearance of 10-year-old Katherine Lyon and 12-year-old Shelia Lyon in 1975. Wednesday, July 15, 2015, in Wheaton, Md. Authorities on Wednesday announced first-degree murder charges against an imprisoned sex offender in the disappearance of two sisters from a suburban Maryland mall in 1975, bringing some clarity to the baffling case that made parents question whether to allow children out of their homes alone. (AP Photo/Molly Riley)  (The Associated Press)

Authorities from Maryland and Virginia are set to announce what they call "significant developments" in the 40-year-old case of two sisters who vanished from a suburban Maryland mall.

Police and prosecutors from Montgomery County, Maryland, and Bedford County, Virginia, will hold a news conference Wednesday in Wheaton, the town from which the Lyon sisters disappeared in 1975. Katharine Lyon was 12, and Sheila Lyon was 10.

Police have named a sex offender, Lloyd Welch, and his uncle, Richard Welch, as persons of interest in the case. Neither man has been charged. Lloyd Welch has denied involvement in the disappearance. Richard Welch has declined to comment.

Authorities have been searching a mountain near Bedford, Virginia, for the sisters' remains and other clues since last year.