As the search for a missing Wisconsin three-year-old extends into its third week, his mother faces additional criminal charges, and police are searching for a vehicle of interest in his disappearance.

An Amber Alert was issued in Manitowoc County for Elijah Vue on Feb. 20. His mother, Katrina Baur, 30, and her boyfriend Jesse Vang, 39, appeared in court this week on child neglect charges. 

On Thursday, prosecutors upgraded Baur's charge to chronic child neglect and added an additional child neglect charge. 

"We have now changed count one to chronic neglect as party to the crime. We have also added count four, which involves neglect to another child who is 6 years old from Feb. 14," Manitowoc County District Attorney Jacalyn LaBre told WISN.

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This is the fourth charge levied against the mother – she also faces two counts of resisting an officer, Fox 6 reported. 

Baur's attorney, Ann Larson, requested that her client's $15,000 bail be lowered on Thursday in Manitowoc County Circuit Court: 

"She's been worried sick, not knowing where her son is," Larson said, according to WISN. 

But Baur's own mother, Jodi Baur, argued against reduced bail in court, WISN reported. LaBre read a written statement from the child's grandmother in court on Thursday. 

"I have known Katrina Baur longer than anyone else as I am her mother," said the statement, read aloud by LaBre.

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"Katrina has struggled with depression and anxiety for many years, has a history of erratic behavior. She has been suffering from traumatic brain injury and is highly likely to forget mandatory appearances.

"I don’t feel it’s worth the risk to lower her bond, especially as a victim has not been found and many questions have not been answered. She does need to be held accountable for what rules out in the future and I feel releasing her she would be a flight risk."

Vang, who qualifies for public defender representation but has not yet been assigned counsel, also requested that his bail be reduced:

"Yeah, I just got a question," Vang said, according to WISN. "I want to put in a motion for bail reduction." 

Vang was charged with one felony count of party-to-a-crime child neglect and is being held on a $20,000 cash bond.

Prosecutors said Baur would send Elijah to her boyfriend, Vang, for disciplinary purposes because she wanted to teach her toddler to "be a man." 

Among "punishments" Elijah endured were cold showers and standing for hours while praying in time-out, authorities said. 

An amended criminal complaint obtained by Fox News Digital gives insight into Elijah's abuse and the days before his disappearance. 

After reviewing Baur and Vang's messages via text and Facebook, prosecutors say the two were discussing meeting at Vang's apartment to have sex on Feb. 13. Vang told Baur that the three-year-old could "be placed in the bathroom while they have sex," per the complaint. 

When Baur arrived at Vang's apartment at 2:30 a.m. on Feb. 13, prosecutors said, she left her older six-year-old child unsupervised in her car. 

At 3 a.m. the next day, according to the complaint, a photograph from Baur's phone was taken of Elijah "laying down on a bed" with a "blindfold over his eyes." The toddler appeared to "have bruising on his jawline and neck on the left side, as well as bruising on his upper arm." 

Elijah was reported missing on Feb. 20 by Vang, who told police he had taken a nap and took the boy into the bedroom with him, but that the child was gone when he woke up about three hours later, the Associated Press reported.

Combined rewards for Elijah's recovery have risen to $25,000, with Manitowoc County Crime Stoppers offering $10,000, and the FBI offering $15,000, for information leading to the location and return of the child or the arrest and conviction of those responsible for his disappearance. 

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On Monday, police said they had seized a car of interest – a beige 1997 Nissan Altima with WIsconsin plates beginning with "A" and ending in "0" – in the child's disappearance. Now, police are asking home and business owners to scour any surveillance footage taken on Feb. 19 between 2 and 9 p.m. for the vehicle, according to Fox 6.

Vue, who is of Hmong descent, is three feet tall, has dark blond hair and brown eyes and weighs about 45 pounds, police say. He has a birthmark on his left knee and was last seen wearing gray sweatpants, a long-sleeved, dark-colored shirt, and red-and-green dinosaur slip-on shoes. 

Anyone with information is asked to contact police at 844-267-6648 or 920-686-7200. You can also submit a tip online at tips.fbi.gov.