GERMANTOWN, Md. (WNEW) — It’s been a year since 3-year-old Sarah Hoggle and 2-year-old Jacob Hoggle disappeared with their mother in Montgomery County.

Police don’t believe the children are still alive, but there is still no evidence to prove otherwise.

Authorities and volunteers have spent days searching for the siblings over the past year — seven miles of roadside and railroad tracks were canvassed, Little Seneca Lake was scanned and areas throughout northern Montgomery County were combed. They have found nothing.

Catherine Hoggle, who has a history of paranoid schizophrenia, is charged with child neglect and obstruction in connection with their disappearance. She’s currently in custody at a psychiatric hospital, and has refused to tell authorities what happened to the children. She’s due back in court later this month, but she’s previously been ruled incompetent to stand trial.

Jacob was last seen with Catherine on Sept. 7, 2014, and Sarah was last seen with her on Sept. 8, 2014.

According to their father, Troy Turner, Catherine took the kids to visit her mother on Sept. 7. She said she went out for pizza with Jacob, but came back without him, claiming she dropped him off at a playmate’s house.

The next morning, at home, Turner says he woke up to find that Sarah was gone, too. Catherine told him she had dropped the children off at daycare.

That afternoon, Catherine said she couldn’t remember where the daycare was. Turner says he decided to go to the police, but Hoggle asked to stop at a Chick-fil-A for a drink and slipped out of the restaurant when he wasn’t looking. She vanished for four days before being found and arrested. She has been in custody ever since.

WNEW’s Chuck Carroll spoke with Turner leading up to the anniversary of Sarah and Jacob’s disappearance, about mental illness, heartbreak, and many unanswered questions.

PART I – The Calm Before the Storm

When Troy Turner first met Catherine Hoggle at the restaurant where they both worked, she seemed like a normal, healthy college student. It wasn’t until she got pregnant with their first child that problems started to arise.

PART II – Catherine Disappears With Sarah and Jacob

Catherine appears to be improving after her stay at a psychiatric facility, but Troy wakes up one morning to find Sarah and Jacob are missing. Soon afterwards, Catherine disappears, too.

PART III – The Desperate Search Begins

Once Troy realizes his children are likely in danger, his desperate search for the kids begins. When Catherine re-appears and there is still no sign of the children, his panic deepens.

PART IV – Optimism Wanes, Police Assume the Worst

After weeks go by and there’s no sign of the kids, it’s a tough thought for a still-optimistic Troy to stomach when the police start treating the case as a homicide.

WNEW’s Chuck Carroll contributed to this report. Follow him and WNEW on Twitter.