The Los Angeles Police Department's online crime map intended for public use has failed to include nearly 40% of serious crimes reported in the city, a Times analysis has found.
The omissions, which date back at least six months, include thousands of crimes known to LAPD officials and are included in their official crime statistics.
Among the 19,000 incidents between Jan. 1 and June 13 that do not appear at lapdcrimemaps.org:
10,766 personal, vehicle or other nonviolent thefts
In one of those rapes, a man hid in the back of a woman's car, forced her to drive to an abandoned North Hollywood apartment and assaulted her. It was the kind of incident that residents of the neighborhood around Sherman Way and Kester Avenue would have wanted to know about.
The March 26 attack was reported on the LAPD's blog but has yet to show up on the public map.
The lapses mean that the map, touted by city leaders as an important and innovative resource for city residents to determine whether their neighborhoods are safe, presents a drastically incomplete image of city crime.
Some residents have tried to bring the problem to the department's attention, to no avail. Jason Insalaco, a former resident of Atwater Village who uses the pen name GlendaleBlvd, posted a message about unmapped crimes in that area on a neighborhood message board earlier this year, but his concerns were dismissed by the department. He said he was outraged by the site's inaccuracies.
"The community is not being accurately informed," Insalaco said. "They are being misled and lulled into a false sense of security."
The Times discovered the magnitude of the problem while developing its own online map to display LAPD data. Comparing the LAPD map with the department's official totals revealed that thousands of crimes through mid-June were missing. The department's official crime tally recorded more than 52,000 serious crimes this year. But the database on the public mapping site contained fewer than 33,000 for the same period.
Among the omissions, caused by a programming error, were more than a thousand violent robberies, including two out of seven street robberies committed in April and May by men posing as police officers.
The Times informed the LAPD last week of the discrepancy and specific examples of missing crimes.
This week, the LAPD added about 20,000 crimes from 2009 to data it provides The Times. But as of late Wednesday, those additions had yet to appear on the LAPD map.
"The department is looking into the issue that you brought to our attention," said Lt. Rick Banks, the officer in charge of the online unit. "When we come up with our findings, we will respond to you."
Banks declined to say whether the crimes were lost before the information was sent to the private contractors who produce the maps or whether the problems took place when the contractor processed the data. It was also unclear whether the problem dated to the origin of the project or was more recent.
The missing crimes mark the second major problem with the LAPD's public maps. In April, The Times found that programming errors by the LAPD's contractor had caused thousands of crimes to be mapped in the wrong place, mistakenly portraying the Los Angeles Civic Center as the most crime-ridden location in the city. To resolve the problem, the contractor has dropped those crimes from the map, but has not yet placed them in their correct locations.
When the LAPD launched the mapping site in March 2006, it was promoted as a publicly accessible version of Chief William J. Bratton's vaunted CompStat system. CompStat is a computer-powered tracking process first developed under Bratton at the New York Police Department that uses maps to track crime trends and guide deployment.
The internal CompStat system is managed by LAPD staff, and CompStat's top official emphasized that the problems with the public system had not affected the department's internal statistics.
"It's not something we had anything to do with," said Det. Jeff Godown, head of LAPD's CompStat unit. "It is what is. It's for the general public. For what we do [at LAPD] we have a much more robust thing."
By contrast, the map available to the public at lapdcrimemaps.org is a joint venture between the Web development firm LightRay Productions and the engineering company PSOMAS, which manages it. Together, the two companies market a product known as ePolicing, which sells the mapping application first built for LAPD to other police departments.
In an e-mail to The Times late Wednesday, PSOMAS Vice President Craig Gooch said his company had identified an inadvertent programming error and fixed it. However, reported crimes continued to be missing from both the LAPD map and data sent t oThe Times.
The public map, which includes an e-mail notification service, was created as part of an overhaul of the LAPD's website funded with $362,000 raised by the Los Angeles Police Foundation.
The scale of the errors undermine the LAPD's expressed purpose in publishing the information. LAPD officials have said that a key reason for publishing the maps is so that residents can spot crime trends.
But earlier this year when the so-called Salt & Pepper Bandit robbed 13 Los Angeles banks in less than a month, only six of the heists found their way onto the LAPD map.
In Atwater Village, Insalaco and other residents saw that about half the crimes reported by the news media had failed to appear on the LAPD's site. But when their concerns about a "massive misinformation campaign" came to the attention of local police officials, Northeast Division Capt. William A. Murphy dismissed them.
"The simple answer -- no," Murphy wrote in an April 22 newsletter responding to Insalaco's allegations. "There is no way that we under report crimes in [the Northeast division] by 50%."
Contacted Wednesday, Murphy said he was troubled by the map's flaws.
"From my perspective, any time it's even slightly off, that can cause a question on all the statistics," Murphy said.
He conceded, though, that he did not check the map for accuracy even though he urged community groups to use it.
"I'm a police officer, I'm relying on the technology," Murphy said. "I'm not an expert on computer systems."
Those who are experts on technology say data omissions on this scale suggest a lack of attention to accuracy.
It means "someone was not being particularly concerned about their data quality," said Clay Johnson, director of software development for the nonprofit Sunlight Foundation, which republishes government data online and urges the government to release more.
Still, Johnson commends government agencies that make an effort to post data online.
Although he called a 40% data loss a big problem, he added that some level of error is unavoidable when working with complicated databases.