"We just consider our mom lost," her daughter, Lynn Young of Aurora, said. "It just feels like we don't have closure."

Young mailed the urn from a post office in Sun City, Ariz. on Jan. 28.

"My sister said, 'Whatever you do, don't ship it through the United States Postal Service,'" Young said.

But FedEx and UPS don't accept cremated remains. And the Transportation Security Administration will allow them only as a carry-on item and they must be removed from a metal urn.

The package's tracking number shows it was checked into the massive sorting facility in North Denver on Jan. 31. Then it disappeared.

The shipping label arrived in Young's mailbox that week. There was no package, just the tag.

"It's upsetting and it's even hard to talk about," Young said. "When it's something as important as your mom's urn, it's not like it's a book from Amazon that they lost, or something like that, where you can just order another one. This is something that can't be replaced."

Young described the Postal Service as "not very responsive" until she contacted 9Wants to Know investigator Kyle Clark, who called the Postal Service on her behalf.

"Now, they're awesome," Young said. "I've got the inside track and really helpful people that seem like they're personally working on it."

David Rupert, a Postal Service spokesman, said in a written statement: "The Postal Service is very concerned about all mail, but especially this piece because of the obvious sentimental value. We are doing all we can to find it [and are] confident that it will be located."

The Postal Service requires that cremated remains be sent by registered mail, which keeps packages out of the bulk delivery system. Young was unaware of the procedure and she says the clerk did not ask her the specific contents of the package.

Rupert says despite the error, the package should have been delivered. He promised a full-court press to find the package after the holiday weekend.

The package could still be at the sorting facility in North Denver, or because the tag fell off, it could have been routed to the Postal Service's lost mail warehouse in Atlanta. Or, because the box had an old UPS tag on it, it might have been turned over to UPS by postal employees.

9Wants to Know will continue to follow this story and provide an update if the urn is located.

(KUSA-TV © 2012 Multimedia Holdings Corporation)