Napa Cold Case Unit Closes 1991 Killing

The man who murdered an American Canyon store owner in front of her 14-year-old daughter in 1991 has been identified, but will never face justice for the crime: He died in prison for bank robbery 18 years ago, according to Napa County detectives.


More than 21 years after an American Canyon shopkeeper was fatally stabbed as she tried to stop a robber, her killer's name is finally known.

The belief that they could still solve Kin Po Ko's 1991 killing was the driving force behind the Napa County cold case unit, which disbands Friday with the conclusion of its two-year grant to investigate 39 unsolved homicides and rapes, according to a press release issued Thursday by Capt. Leroy Anderson of the county sheriff's department:

On 3/23/91 a homicide occurred at Sam’s Market in American Canyon. The victim, Kin Ko, was a 38-year-old female. Ko and her husband owned and worked at the market. 

At the time of the homicide, Ko’s 14-year-old daughter was working behind the counter with her. The homicide occurred during the course of a robbery at the store. 

A male suspect entered the store and approached the front counter to make a purchase. At the same time a second suspect stood in the doorway of the business, most probably as a lookout. 

The suspect at the counter brandished a knife, and held Ko at bay while he removed cash from the register. After taking the cash the suspect backed away from the counter to leave. 

Ko produced a handgun from behind the counter and ordered the suspect to stop. Ko approached the suspect and attempted to take the cash from his hand. 

A struggle between Ko and the suspect ensued and they fell to the floor. During the course of the struggle, Ko was stabbed once in the back. 

The suspect fled the store and Ko got up to give chase. Ko soon returned to the store and collapsed inside the doorway, mortally wounded. 

During the course of the robbery, Ko’s daughter called 911 for help. Responding Deputies were close by and upon arriving to the scene, witnessed Ko collapse inside the doorway. 

A Deputy rendered aide to Ko while another Deputy immediately checked the area for suspect(s).  Ko was transported to the hospital where she died from the inflicted knife wound injury. 

During the course of the investigation, witnesses were contacted and they provided a description of the suspect(s). 

A forensic sketch artist was able to produce two composites of the suspects, which was then generated to the public.  Leads from witnesses directed Detectives to possible suspects from the American Canyon area. Numerous witness statements were taken by the original investigators. 

At the time of the initial investigation, Detectives attempted to locate a potential suspect identified as Michael Lantz of American Canyon/Vallejo. 

Lantz was on parole around the time of the homicide and resembled one of the suspects in the sketch.  Detectives were not able to locate Lantz for over a year after the homicide.  

When the Napa Sheriff Criminalist processed the original crime scene, the suspected murder weapon was found on the floor of the store and later brought back to the lab. 

Traditional forensic processing methods (ie. Latent print processing) available in 1991 were applied to the bloody knife, however no useful forensic evidence was identified. 

DNA processing was in its infancy around 1991 and not the developed science it is today. In 1991, Criminalists required large quantity samples of evidence such as blood to do any effective processing. 

The criminalist was able to identify a serial number on the knife which directed the investigators to a local tool salesman. 

The salesman gave investigators records showing that the knife had been recently purchased by a family member of Michael Lantz. 

The investigation was greatly hampered by the investigators’ inability to locate Lantz for over a year after the crime.  Detectives spent a great deal of time and resources at the time investigating the case and attempting to locate Lantz, who was eventually found in another County. 

Evidence produced from the original investigation indicated that Lantz was a primary suspect in a series of armed robberies of small convenience stores and gas stations in the American Canyon and Vallejo areas near the time of the robbery/murder at Sam’s Market. 

Leads were exhausted in the original case, and with little evidence to support a criminal filing, the case went cold. 

In 2009, a Napa Sheriff Detective reviewed the case and believed the case could be solvable. The Detective reviewed a few other cases and felt perhaps other unsolved homicides might benefit from additional review. 

The Detective attended a Cold Case Seminar and learned about a Cold Case Grant available to law enforcement agencies. The homicide of Kin Ko in 1991 was the driving force behind applying for the grant that was ultimately obtained to fund the Napa County Cold Case Unit in 2010. 

Det. Todd Shulman from the Napa Police Department and Det. Pat McMahon from the Napa Sheriff’s Office, worked full-time in the Napa Cold Case Unit from October 2010 through June 2012. 

Hundreds of hours and many resources were poured into the investigation of these unsolved murders and sexual assaults.  Many articles of evidence from these Cold Cases had never been subjected to modern DNA analysis. 

The Kin Ko murder was one of these Cold Cases that had crime scene evidence reviewed with modern DNA analysis. 

In 2012, Det. Shulman and Det. McMahon received results from the Kin Ko murder. DNA evidence linking Michael Lantz to the crime was located on the murder weapon found at the scene. 

A new investigation into the Kin Ko murder was activated utilizing the Napa County Major Crimes Task Force. Detectives from Napa PD, Napa Sheriff and the Napa DA’s office participated in the investigation. Detectives re-interviewed old witnesses and identified new witnesses. Detectives travelled out of state to interview some witnesses.

During the course of the investigation, Detectives Shulman and McMahon learned the primary suspect, Michael Lantz, had died in Federal Prison around 1994.  At the time of Michael Lantz’ death, he was incarcerated for a bank robbery. 

Detectives were not able to positively identify a second suspect or how that person was involved in the crime.  There was no physical evidence located linking a second suspect to the crime. 

Sadly, Ko’s husband passed away a short time after Ko’s murder. The surviving Ko family was notified of the circumstances surrounding their mother’s murder and the identity of the person suspecting of killing her, allowing some final closure to be found for the Ko family. 

For more about Napa County's unsolved disappearances, homicides and rapes, please see our Cold Cases topic page at napa.patch.com/topics/cold-cases.

For the latest reports on crime and arrests in Napa, please see our Police & Fire section, available from the News tab above and at napa.patch.com/police-fire.

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Wayah June 29, 2012 at 02:28 AM
It is good that the family finally has closure regarding this incident.. Kudo's to Napa's Cold Case Unit and to the Napa Register for the update....
john s. mccullough July 02, 2012 at 09:14 PM
It is important that the public recognize that our law enforcement organizations and respective LE individuals never give up. As far as I am concerned they got their man. My sympathies to the family. The measure of closure is at least something, but, of course, nothing will replace the loss.


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