More than 125 personnel from 12 agencies took part in Monday's search. They focused on the area between Highway 128 and Highway 93, including Eldorado Canyon in Boulder. Eight to 10 U.S. Immigration and Customs Enforcement officers also participated in the search Monday.
Investigators worked with bloodhounds and used two teams of four to search the areas that were already been cleared.
Crews also searched along Highway 36, it was announced Monday during a press conference.
Police confirmed a backpack found in a Superior neighborhood Sunday belongs to Jessica.
The Colorado Bureau of Investigation will be testing the backpack for additional evidence. Police say that the backpack was found in the Rock Creek subdivision, 6.2 miles from Jessica's house. 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. 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 Saturday.
On Saturday, a dive team went into Ketner Reservoir in order to rule the area out in the search.
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."
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, 9NEWS affiliate KSHB-41 in Kansas City 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 says Jessica's father, Jeremiah Bryant, is devastated and beside himself that his daughter is missing. She says 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.
Officers patrolled Jessica's elementary school on Monday. Police and parents took every precaution as they hoped for Jessica's safe return.
"It's very scary," Natalie Madrid said. "I'm a single mother of three."
"It's just an eye opener," Madrid added. "You need to protect your kids. You need to make sure your kids are where they need to go. It's devastating, and it's scary."
"I can't imagine what their mother is going through," Madrid said. "It could happen to any parent."
Jessica's disappearance is just frightening for her classmates and friends.
"They're just wishing she could come home safe," sixth grader Nick Ramirez said. "They talked about it all day."
Ramirez says many of his classmates talked to counselors Monday.
"[I'm] sad and scared at the same time," Ramirez said. "It's so close to home."
This is not the first scare close to the elementary school. On Memorial Day weekend, a woman escaped an attempted kidnapping at Ketner Lake.
The 22-year-old told Westminster Police a man put a rag over her mouth that smelled like chemicals and tried to grab her. Police never found him. Ketner Open Space is less than half a mile from Chelsea Park - where Jessica disappeared. Police are not saying if they suspect a connection, but it's enough to make some parents nervous.
"That's two incidents in the neighborhood," Sergio Ramirez said.
Ramirez says it's enough to make any parent nervous.
"[It's] the unknown," Ramirez said. "That's for sure."
More than anything, Ramirez wants Jessica to come home safely.
"She needs all of our prayers," Ramirez said.
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. Find out more requirements for an Amber Alert here, http://1.usa.gov/QPQf3C.
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.
Authorities are monitoring social-media sites and following up on more than 300 tips.
HOW YOU CAN HELP
A new flier with updated information was distributed Monday. It shows Jessica with and without her glasses.
Police have been updating volunteers and the public through their Twitter page. You can follow the Westminster Police here: https://twitter.com/WestminsterPD
Police released a phone number and email for anyone with information: 303-658-4336 and PDamberalert@cityofwestminster.us.
Two vigils for Jessica are planned for Tuesday at the following locations:
10200 Countryside Drive
Vigil begins at 7 p.m.
Rock Creek Superior Community Park
Between Coalton Road and Indiana Street
Vigil begins at 7 p.m.
For both vigils, individuals are asked to bring flashlights or a cellphone, do not use candles.
(KUSA-TV © 2012 Multimedia Holdings Corporation)