Blood belonging to the missing mother of a Today Show host was found on the porch of her home, police said.

There are still no prime suspects in the disappearance of Nancy Guthrie, whose daughter is Today show host Savannah Guthrie.

During a press conference on Thursday, Chris Nanos, a Pima County sheriff, said police had confirmed that blood found on the porch following her disappearance was Ms Guthrie’s.

It was also announced that the FBI is offering a $50,000 (£37,000) reward for information leading to her safe return.

Authorities say they are in a race against time to save Nancy Guthrie, who is thought to have been abducted in her sleep from her home on Saturday night, leaving behind life-saving medication.

Drones, a helicopter equipped with an infra-red camera, search-and-rescue dogs and volunteers have spent days searching for the 84-year-old, so far without success.

Donald Trump said he was sending the director of the FBI, Kash Patel, to help investigate the disappearance.

The US president said: “I spoke with Savannah Guthrie, and let her know that I am directing ALL Federal Law Enforcement to be at the family’s, and Local Law Enforcement’s, complete disposal, IMMEDIATELY.

“We are deploying all resources to get her mother home safely. The prayers of our Nation are with her and her family. GOD BLESS AND PROTECT NANCY!”

Mr Patel was already heading to Arizona for a previous engagement, but a source told Axios he was “devoting all resources possible to help” and was “prepared to go if the situation warrants”.