The FailureFailure
Four police agencies each held one part of the same case
The short answer
What is linkage blindness?
Linkage blindness is the failure of police agencies to share information on unsolved murders across jurisdiction lines and to link those murders to one offender.14 Criminologist Steven Egger used the term in the title of a 1984 article on serial murder.25 The FBI’s national database for linking violent crimes, ViCAP, has operated since 1985.316
Chain · The Failure
Four attacks, four agencies
- The line
- Event
- Open case
Notation
- The line
- Time, left to right. Down the screen on a phone.
- Event
- A fact on the record.
- Missed chance
- The system had him and let him go.
- The catch
- The error that ended it, knocked out of line.
- Open case
- No one charged.
- A wait
- Time passes and nothing moves.
Data table
| Step | Detail | Notation |
|---|---|---|
| Solano County Sheriff | Dec 20, 1968 · Lake Herman Road | Event |
| Vallejo Police | Jul 4, 1969 · Blue Rock Springs | Event |
| Napa County Sheriff | Sep 27, 1969 · Lake Berryessa | Event |
| San Francisco Police | Oct 11, 1969 · San Francisco | Event |
| Never caught | case unresolved | Open case |
Where does the term come from?
The term appears in the title of Steven Egger’s article “A Working Definition of Serial Murder and the Reduction of Linkage Blindness,” published in the “Journal of Police Science and Administration” in September 1984.26 The record of his 1990 book defines it as police failure to link various murders to a single perpetrator.45
Criminologist Steven Egger, a specialist in serial homicide, published “A Working Definition of Serial Murder and the Reduction of Linkage Blindness” in the “Journal of Police Science and Administration” in September 1984.25 The U.S. Justice Department’s library record states its argument: the extent of serial murder is an indirect effect of an almost total lack of sharing or coordination of investigative information on unsolved murders.2
The record of his 1990 book, “Serial Murder: An Elusive Phenomenon,” defines the term as police failure to link various murders to a single perpetrator.45 A law enforcement encyclopedia gives the cause: an officer’s responsibility stops at the boundary of the jurisdiction, except in hot pursuit, and an agency ends up not sharing information on unsolved murders with other agencies.1 A 2024 review of crime linkage research by two Purdue University researchers cites Egger’s 1984 article for the term.6
How did four agencies come to hold one case?
Four attacks in Northern California between December 1968 and October 1969 were handled by four agencies: the Solano County Sheriff, Vallejo police, the Napa County Sheriff and San Francisco police.789101113 Five people were killed and two survived.713 The case, known in the press as the Zodiac case, is open.7815
David Faraday and Betty Lou Jensen were shot on Lake Herman Road in Solano County on December 20, 1968.7911 Darlene Ferrin was shot in a parking lot at Blue Rock Springs in Vallejo on July 4, 1969, and the man with her was wounded.71011 Cecelia Shepard was stabbed at Lake Berryessa in Napa County on September 27, 1969, and later died, while the man with her survived.7101113 Paul Stine, a taxi driver, was shot in San Francisco on October 11, 1969.711
Authorities have confirmed four attacks, with five people killed and two survivors.713 A different agency handled each attack.791011 News film of the first includes an interview with a Solano County Sheriff’s detective sergeant, and Vallejo police took a call from a man claiming the second.910 A Napa County Sheriff’s investigator began work on the third the day it happened, and the San Francisco Police Department holds evidence from the fourth.71112
Nine days after the fourth attack, a San Francisco police captain held a press conference on sharing information and cooperating with other jurisdictions.714 The offender was never caught.711 The FBI’s San Francisco office said in December 2020 that the case remains an ongoing investigation.815
In 2018 a former San Francisco homicide detective who had worked the case told the Sacramento Bee she was unaware of any agencies working on it collectively.13 A Napa County Sheriff’s lieutenant said his agency was not actively investigating and followed tips as they arose.13 In December 2020, CBS San Francisco and the Associated Press reported that Vallejo, Napa County and Solano County had open case files, as did the California Department of Justice.8
What did the FBI build in response?
The FBI states the problem: when a serial offender strikes in different communities, information about the crimes is stored separately in the files of various local police agencies.16 The FBI credits the idea for a shared system to Pierce Brooks, a Los Angeles homicide investigator who searched newspapers at a public library for murders like the ones he was investigating.1617 It says he became the first program manager of the Violent Criminal Apprehension Program, ViCAP, in the summer of 1985.316
The FBI describes ViCAP as the national repository for violent crimes: homicides, sexual assaults, missing persons and unidentified human remains.16 Its first focus was serial killers who crossed jurisdictional boundaries.3 Investigators from participating agencies enter the details of a case into the database.16
The record of Egger’s 1984 article says the system was then being developed and that its success would depend on local law enforcement cooperation.2 ProPublica reported in 2015 that about 1,400 of roughly 18,000 U.S. police agencies took part, that the database received reports on far less than 1 percent of violent crimes committed each year, and that reporting to it was largely voluntary.17
What happens when one department holds the whole file?
Six people were killed in New York City in 1976 and 1977, from Donna Lauria to Stacy Moskowitz, and seven were wounded.1819 One department led the hunt: the New York Police Department’s chief of detectives oversaw a task force, Operation Omega.1819 By one count reported by the Associated Press, it involved 75 detectives and more than 200 uniformed officers.18
Its detectives had to sort through a flood of reports about possible suspects.1921 Detectives arrested David Berkowitz as he left his Yonkers home on August 10, 1977.181921 He pleaded guilty to the six murders on May 8, 1978.1921
The structures differed. In New York, reports about suspects reached one task force.19 In Northern California, each agency kept its own case file.8
The rule
The offender crossed jurisdiction lines. The files stayed on their own sides.
Questions
Who is credited with the term linkage blindness?
- A 2024 review of crime linkage research credits criminologist Steven Egger, citing his September 1984 article in the “Journal of Police Science and Administration,” which has the term in its title.256 The Justice Department’s record of the article notes an earlier version presented in March 1984.2
Is the 1968–1969 Northern California case solved?
- No. The offender was never caught.711 The FBI’s San Francisco office said in December 2020 that the case remains an ongoing investigation.815 Authorities have confirmed four attacks, with five people killed and two survivors.713
What does ViCAP stand for?
- ViCAP is the FBI’s Violent Criminal Apprehension Program.316 The FBI describes it as the national repository for violent crimes, specifically homicides, sexual assaults, missing persons and unidentified human remains.16 It has operated since 1985.316
The record
Sources
“Serial Murder Investigation,” in L. E. Sullivan, M. S. Rosen, D. M. Schulz and M. R. Haberfeld (eds.), Encyclopedia of Law Enforcement (SAGE Publications; online edition dated Sep 15, 2007), DOI 10.4135/9781412952415.n176. Supports: linkage blindness as agencies not sharing information on unsolved murders.
S. A. Egger, “A Working Definition of Serial Murder and the Reduction of Linkage Blindness,” Journal of Police Science and Administration 12(3), September 1984, pp. 348-357. Abstract record NCJ 95075, NCJRS Virtual Library (U.S. Department of Justice, Office of Justice Programs), archived copy of Nov 12, 2025. Supports: author, title, journal and date of the article.
FBI, “ViCAP Goes Online” (FBI news story, Aug 4, 2008; FBI archives, archived copy of Jan 30, 2026). Supports: ViCAP operating in 1985.
S. A. Egger, “Serial Murder: An Elusive Phenomenon” (Praeger Publishers, 1990). Abstract record NCJ 123588, NCJRS Virtual Library (U.S. Department of Justice, Office of Justice Programs), archived copy of Dec 6, 2025. Supports: the definition of linkage blindness.
Illinois Center for the Book (Illinois State Library), Illinois Authors, individual author record for Steven A. Egger (undated). Supports: Egger is a criminologist and a specialist in serial homicide.
Vinicius Lima and Umit Karabiyik (Purdue University), “Advancing Crime Linkage Analysis with Machine Learning: A Comprehensive Review and Framework for Data-Driven Approaches,” arXiv:2411.00864v1 (Oct 30, 2024), preprint, not peer reviewed. Its references [21] and [22] are Steven A. Egger’s 1984 article. Supports: a 2024 review by two Purdue researchers cites Egger (1984) for the term; ViCAP dates to 1985.
Ryan Ocenada and Kevin Fagan, “Zodiac Killer: Why sleuths are still obsessed with S.F.’s most notorious serial killer” (San Francisco Chronicle, Oct 22, 2023). Supports: four confirmed attacks, five killed, two survived.
CBS San Francisco / Associated Press, “Zodiac Killer’s Cipher Solved By Amateur Codebreakers” (Dec 11, 2020). Supports: five killed between December 1968 and October 1969; the FBI San Francisco office’s statement that the case remains an ongoing investigation; Vallejo, Napa County and Solano County open case files, as well as the California Department of Justice.
Bay Area Television Archive, San Francisco State University, “Double Murder of Faraday & Jensen (Zodiac),” catalogue entry for KRON-TV newsfilm aired Dec 21, 1968. Supports: the Solano County Sheriff’s Department investigated the first attack.
Katie Dowd, “Will DNA submitted to genealogy sites also finally catch the Zodiac Killer?” (San Francisco Chronicle, May 1, 2018; updated Feb 19, 2019), photo-gallery caption. Supports: Vallejo police received the call claiming the second attack.
Marsha Dorgan, “Tracking the mark of the Zodiac for decades” (Napa Valley Register, Feb 18, 2007). Supports: dates and places of the attacks; Lake Berryessa in Napa County; Cecelia Shepard died two days later; a Napa County Sheriff’s investigator began work on Sep 27, 1969; never caught.
Bay Area Television Archive, San Francisco State University, “Zodiac Killer: Lake Berryessa Attack,” catalogue entry for a KPIX report of Sep 30, 1969. Supports: the third attack was in Napa County and the Napa County Sheriff’s office spoke for the investigation.
Anita Chabria and Ryan Sabalow, “Can DNA identify the Zodiac Killer now that it has revealed the East Area Rapist suspect?” (The Sacramento Bee, May 2, 2018, as carried by the Napa Valley Register). Supports: seven victims, five killed, two survivors; the 2018 statements of a former San Francisco homicide detective and a Napa County Sheriff’s lieutenant.
Bay Area Television Archive, San Francisco State University, “Captain Lee on Zodiac Case Cooperation,” catalogue entry for KRON-TV newsfilm aired Oct 20, 1969. Supports: the Oct 20, 1969 press conference on sharing information.
Dan Noyes and Kayla Galloway, “Zodiac Killer’s ‘340 Cipher’ sent to SF Chronicle 51 years ago reportedly solved by code experts” (ABC7 News, KGO-TV San Francisco, Dec 12, 2020), reporting the FBI’s statement to the station. Supports: the FBI describes the case as an ongoing investigation.
FBI, “ViCAP: Fighting Violent Crime for 25 Years” (FBI news story, Aug 26, 2010; FBI archives, archived copy of Jan 30, 2026). Supports: the FBI’s statement of the problem.
T. Christian Miller, “The FBI Built a Database That Can Catch Rapists - Almost Nobody Uses It” (ProPublica, co-published with The Atlantic, Jul 30, 2015). Supports: participation in ViCAP as of 2015.
Michael R. Sisak, “NYPD commander who took ‘Son of Sam’ confession dies at 99” (Associated Press, Sep 20, 2019, as carried by the Las Vegas Sun). Supports: one department; six killed, seven wounded, 1976 and 1977.
History.com, “Son of Sam serial killer is arrested” (A&E Television Networks, published Feb 9, 2010; updated Nov 7, 2025). Supports: the arrest on Aug 10, 1977; six killed and seven wounded.
FBI Records: The Vault, “The Zodiac Killer,” listing of released FBI records, Parts 01 to 07 (archived copy of Mar 13, 2026). Supports: the FBI has published its file on the case in seven parts.
John Philip Jenkins, “David Berkowitz” (Encyclopaedia Britannica, last updated Dec 2, 2025; archived copy of Jan 9, 2026). Supports: the arrest on Aug 10, 1977; detectives sorting through reports of suspicious persons; the guilty plea on May 8, 1978.
Educational analysis. Adjudicated cases only. Victims named with respect.