Aurora police detectives on Tuesday fielded scores of tips about the brazen kidnapping of an 8-year-old girl from her bedroom window but said they were no closer to knowing the identity of the suspect.

Experts say such stranger abductions are rare. There are about 115 such kidnappings of children in the United States each year, according to the National Center for Missing and Exploited Children.

Rarer still are cases such as Monday’s, in which police said a man, seeing the girl through her unlocked window, removed the window screen and grabbed her. She screamed, struggled and escaped, drawing her father outside to find her running toward the front of the house from an alley.

“These are not cases we typically see,” said Robert Lowery, the executive director of the center’s missing children division, which has offered resources to Aurora police as they continue the search. More common are stranger abductions like that of 10-year-old Jessica Ridgeway, who was kidnapped and killed a year ago while walking to school in Westminster.

“This is a very bold offender. Someone out there is going to recognize this composite,” Lowery said. “We’re hopeful they’ll get a quick resolution to this case and certainly before this offender would act out again.”

“That little piece”

As investigators vetted more than 50 tips, some more promising than others, police also announced that a reward for information about the case had been doubled to $20,000, the highest in the department’s history.

“When you’re in a situation like this, where we have absolutely no idea who this person is … you rely on all the tips that come in,” said Sgt. Cassidee Carlson, a department spokeswoman. “We just need that little piece that gets us going on the right track.”

Detectives from the crimes against children unit immediately began trying to look at similar incidents in the metro area but found none.

“There have been no other cases like this,” Carlson said. “It’s a scary situation. That’s why we’re handling it in the way we are. We need to get this guy off the street.”

Abductions are more common when children are walking to and from school, Lowery said. In any case, assertive children such as the 8-year-old girl, who scream and kick and bite, are more likely to break free.

“We tell parents to teach your children that if someone tries to take them, bring as much attention to the situation as you can,” Lowery said.

BMW sought

Police described the suspect as a white man with blond hair, wearing a black winter jacket. He had the strong odor of cigarette smoke. The girl’s father saw what appeared to be a newer-model BMW sedan speeding out of the alley near the home in the 1600 block of Hanover Street.

Offering the reward are Crime Stoppers, the Aurora Police Reward Fund and SungateKids Child Advocacy Center, which employs forensic interviewers who specialize in dealing with children. Police said Shortline Automotive put up the additional $10,000 that allowed the reward to be doubled.

Sadie Gurman: 303-954-1661, sgurman@denverpost.com or twitter.com/sgurman

Stranger abductions

The National Center for Missing and Exploited Children studied 7,000 attempted abductions between February 2005 and January 2012:

72% involved a suspect in a vehicle

35% happened while a child was walking to or from school or a related activity

69% involved a female child

53% of the children simply walked or ran away with no physical contact

19% involved “Good Samaritan” intervention

32% lured by the offer of a ride

12% lured by candy or sweets

8% asked the child a question, offered money or

said they were looking for a lost pet