The National Center for Missing and Exploited Children launched a campaign Wednesday that will place the faces of Sarah and Jacob Hoggle on digital billboard and bus shelter displays throughout the D.C. area.

The “Summer of Hope” campaign is designed to spread the word about the young children, who disappeared Sept. 7, 2014, after last being seen with their mother, Catherine Hoggle, in the Gaithersburg area.

Since their disappearance, Catherine Hoggle has been undergoing treatment at a mental hospital for schizophrenia. She has not provided police with any information about the whereabouts of her kids. She is charged with abducting the kids and obstructing the investigation.

Montgomery County police are also building a homicide case against her. In April, a judge ruled that Hoggle remained incompetent to stand trial due to her mental state.

The Summer of Hope campaign partnered with Clear Channel Outdoor Americas to show images of Sarah, 3, and Jacob, 2, and other missing area kids for about four minutes every hour on about 50 bus shelter and 14 billboard digital displays.

The campaign will also feature images of Relish Rudd, an 8-year-old from D.C., who went missing from a D.C. homeless shelter in March 2014, while in the care of a 51-year-old custodian who police say later killed his wife and himself.