DETROIT -

It's been nearly a month since anyone has seen infant Kristian Justice and his sister, 6-year-old Kaylah Hunter, the children of Alicia Fox, a woman who was found murdered in an abandoned home.

Her husband, the father of the children, Erin Justice, is now locked up in Atlanta, accused of murdering Fox, but the kids are still out there somewhere.

Family members say they now have a new plan they are hoping will make a difference.

"We're doing all we can," said Brenda Fields, Fox's aunt. "We don't care. We're out asking people to sign the petition for Kaylah and Kristian. We plan to present it to the Michigan State Police."

The family is soliciting signatures for a petition to get an Amber Alert for the two children. The brother and sister have been missing for three weeks now.

"We need 2,500 signatures. Right now we're short about 800," Fields said.

Meanwhile, behind the scenes, a special task force is trying to find the kids, following up on every single lead that comes in.

"When they follow up on a tip, we go right behind them," Fields said.

Sources told Local 4 that police have received hundreds of calls. Some callers claim they've spotted the kids, but the reports all turn out to be false.

Detectives have been grilling Justice and interviewing family members and witnesses. Sources say investigators believe the kids may be somewhere familiar to Justice. That's why family members want the Amber Alert. They don't want anyone to forget that the children are still out there.

"In my heart I believe they're still alive," Fields said. "We've been out searching for them because we don't know what else to do. And we don't want to sit down and do nothing."