Late last week, for the first time since 10-year-old Jessica Ridgeway disappeared on her way to school, no ground crews combed the acres of open space around her home or other sites hunting for evidence.
Authorities have been reluctant to say whether they uncovered any clues that might point to Jessica's killer during the three large-area searches conducted since she disappeared.
But one thing that is certain: Massive, open spaces with their high brush, hilly terrain and exposure to the elements are among the most challenging crime scenes law enforcement can confront.
And in an environment where evidence can be as subtle as a patch of strangely bent grass, collection becomes a race against time, experts say.
On
Wednesday, wind gusts up to 38 miles per hour whipped through the last active search site where part of Jessica's body was recovered. By Thursday, the large ground searches had stopped as police continued the investigation on other fronts, said Westminster Police Department Investigator Trevor Materasso."Short of new information, we don't have plans to do more of the open-space searches," Materasso said. "Westminster has never had a case that would require such an extensive search in terms of geography or personnel."
Jessica left her Westminster home for school the morning of Oct. 5 but never made it. By the next day, hundreds of civilian volunteers searched the park and open spaces south of her Westminster home and near Standley Lake.
Two days later, authorities discovered her backpack in a Superior subdivision, opening a second search area. And Oct. 11, part of Jessica's body was discovered near Pattridge Park Open Space in Arvada.
Based on search-area boundaries provided by Materasso, an estimated 24 square miles have been searched, with varying levels of scrutiny, by more than 200 officers from more than 40 agencies. Search dogs and remote-controlled helicopters with video and infrared technology aided the investigation.
In an abundance of caution, anything searchers came across was documented and collected like evidence, which is part of the reason high winds that re-littered the search sites became so problematic.
By Thursday afternoon, the trash collecting in the corners of windbreak fences throughout Pattridge Park, east of a landfill, was nearly knee high.
"The environmental conditions are definitely a consideration into where, when and how searches are conducted," Materasso said. "The amount of wind was a factor."
Even before the wind kicked up, evidence recovery would have been made more complicated and labor-intensive by the sites' sizes, uneven terrain and tall ground cover, said Tom Griffin, who recently retired as a Colorado Bureau of Investigation crime-scene investigator after 27 years.
One of the first steps in wide-area searches is for investigators to use what they know of the crime and the route that the killer may have taken to narrow the search area.
"The smaller an area, the easier to keep focused. A broken window, a door that's smashed in — you're pretty limited. You're only going to go a few feet left or right of that point of access," said Griffin, now a consultant. "At an outdoor scene, you're not going to know where that is. A footpath may be a place to start, but in reality, you know you're going to have to spread out."
Evidence can be anything from scraps of fabric or blood trails to things as subtle as a patch of grass that's bent in an unusual way, possibly with a footprint or tire track hiding underneath.
Searchers often walk or crawl side by side at arm's length in lines, grids or some other pattern chosen to least disturb the site, he said.
"It's the needle-in-the-haystack analogy," Griffin said. "You may not even know what you're looking for."
In searches like those conducted in Jessica's case, investigators work against the clock.
Transitory evidence, such as hair and paper, can be picked up by the wind or by nesting animals.
And certain types of DNA — traces deposited on the skin or other smooth surfaces, for example — are more easily deteriorated by exposure to heat and moisture.
"Is it in full sun? Partial shade? What are the temperatures? What's the pH? Is there bacterial action where the evidence might be located?" said Iris Dalley, a retired Oklahoma state investigator who now consults with Griffin for Bevel, Gardner and Associates. "If it's exposed to the environment, you might be degrading your profile."
She also noted that some traditional methods for recovering human remains — such as infrared scanners that pick up heat generated by decomposition — may not work when the victim is a small child.
Authorities have not said whether they've recovered all of Jessica's remains.
Materasso said that without the help of outside law enforcement agencies and other volunteers, a search this size would not have been possible.
Like the April and May search for the body of infant Torrey Brown in a Commerce City landfill or the 2007 search in Denver for toddler Neveah Gallegos' body, cases like Jessica's often bring an outpouring of community support.
The day after she disappeared, more then 800 regular citizens withstood icy weather to look for signs of the little girl in the open spaces around her home.
But as police gathered more information, they needed more skilled searchers, Materasso said.
For the first time, Westminster called on the trained volunteers of the Front Range's search-and-rescue teams, who more typically search for lost hikers and climbers.
More than 100 volunteers over three days used their dog teams, climbing skills and some light rappelling to scan areas not easily reached by walking, said Colorado Search and Rescue Board spokesman Howard Paul.
"Most search-and-rescue teams do this type of search every once in a while. They're unusual but not unheard of," Paul said. "When we're looking for someone in the mountains, we're dealing with someone able to respond or signal to us versus a piece of evidence — and we don't even know what it is. We worked at a much slower, much more focused and intense pace."
Alpine Rescue Team volunteer Becky Brock, an engineer by day, spent two days doing the concentrated type of searches needed to recover evidence in Jessica's case.
She said she's glad to be able to help, either in her normal recovery duties or as a small part of police investigations like this one, she said.
"For me, every time, it doesn't matter what the outcome is. It's nice to be able to help someone or help someone's family have that closure," Brock said.
Jessica Fender: 303-954-1244, jfender@denverpost.com or twitter.com/oh_fender
Anda sedang membaca artikel tentang
Investigators in Jessica Ridgeway murder case look beyond open space
Dengan url
http://badbehaviorhabits.blogspot.com/2012/10/investigators-in-jessica-ridgeway.html
Anda boleh menyebar luaskannya atau mengcopy paste-nya
Investigators in Jessica Ridgeway murder case look beyond open space
namun jangan lupa untuk meletakkan link
Investigators in Jessica Ridgeway murder case look beyond open space
sebagai sumbernya
0 komentar:
Posting Komentar