More than 125 personnel from 12 agencies are taking part in Monday's search. They will focus in the area between Highway 128 and Highway 93, including Eldorado Canyon.
Investigators are once again working with bloodhounds. They are using two teams of four and searching again the areas that have already been cleared.
Crews will also search along Highway 36, it was announced Monday during a press conference.
Police confirm that a backpack found in a Superior neighborhood on Sunday belongs to the missing Westminster girl.
The Colorado Bureau of Investigation will be testing the backpack for additional evidence.
Police say that the backpack was found Sunday afternoon in the Rock Creek subdivision. It was found 6.2 miles from Jessica Ridgeway's house. Bloodhounds sniffed it out and are searching the area.
Authorities don't know when the bag was put there. They are asking parents in the Rock Creek subdivision to talk to their kids to see if they noticed anything out of the ordinary.
Authorities have stationed police officers at schools in the area, though there is no indication other children are in danger.
A new flier with updated information was distributed Monday. It shows Jessica with and without her glasses.
Sunday night a person identifying himself as Jessica's cousin posted the following message on the Facebook page set up for the missing girl:
I have a message from the family (I am her cousin) that I want to be heard by everyone following this facebook and the twitter account.
I want to thank everyone for the incredible support pouring in from all over Facebook and twitter and everyone in the community. Seeing how many people standing together and are looking for my cousin has made me immensely proud and humbled. This is not simply a family crisis, it has evolved into a community crisis and everyone pulling together is truly inspiring. Please share this, with everyone and anyone. Thank you so much."
Three police checkpoints were established in the area Sunday. Police stopped and questioned people as they drove in and out of the neighborhood.
Westminster investigator Cheri Spottke says more than 800 volunteers helped look for Jessica Ridgeway Saturday.
Police have been updating volunteers and the public through their twitter page.
You can follow the Westminster PD here: https://twitter.com/WestminsterPD
On Saturday, a dive team went into Ketner Reservoir in order to rule the area out in the search.
Jessica usually walks three blocks from Moore Street to Chelsea Park where she would meet up with a large group of friends before walking 1.3 miles to school. In that three block radius, she disappeared.
Police say Jessica's mother works an overnight shift and her grandmother watches her at night. When Jessica's mother got home at 7:30 a.m. she saw Jessica off to school at 8:30 a.m., according to 9NEWS reporter Kevin Torres.
Police say they got a late start searching because her mother didn't immediately realize Jessica was missing. Officers say her mother slept through calls from school officials to tell her Jessica was absent.
Westminster police sent out an emergency text alert advising residents to be on the lookout before a system-wide Amber Alert was issued by the CBI Friday evening.
"[We] started activating a lot of personnel to start searching for her," Westminster Police Detective Trevor Materasso said.
An Amber Alert is only issued if authorities fear the child is in immediate danger.
Police say there is no indication that she has been abducted.
Three weeks ago, students at an Arvada school saw a man in a dark sedan trying to lure kids closer to his vehicle. JeffCo schools sent letters out to all of its schools - including Witt Elementary - where Jessica attends school. Police are looking into whether there's a connection.
Jessica's father, who lives in Missouri, has been in contact with police. The father told investigators he does not know what happened to his daughter.
Though he refused to talk with reporters on Saturday night, our affiliate KSHB-41 in Kansas City, MO spoke with Jessica's great-grandmother who says they are doing everything they can to help in the investigation.
"The police asked if they could search my house and I said yes because we'd do anything in the world to get her back," Donna Moss said.
Moss said Jessica's father Jeremiah Bryant is devastated and beside himself that his daughter is missing. She said that there is no custody issue between the parents and says they saw Jessica six weeks ago with her mom and maternal grandmother.
Moss pleaded for Jessica's safe return.
"If you've got her - get her back to her parents. She's a beautiful wonderful little girl and we want her back," she said.
Authorities are monitoring social media sites and following up on more than 300 tips.
Police released a phone number and email for anyone with information: 303-658-4336 and PDamberalert@cityofwestminster.us.
(KUSA-TV © 2012 Multimedia Holdings Corporation with The Associated Press)