Familial DNA Searching and Abandoned DNA Identify the Grim Sleeper Serial Killer

A serial killer dubbed the Grim Sleeper, believed responsible for killing at least 10 people between 1985 and 2007, was arrested yesterday.  Although police had DNA from the crime scenes, they had been unable to match the DNA to any known DNA profile.  Using the familial searching protocol, which California began in 2008, analysts found that the Grim Sleeper’s DNA was similar, though not identical, to a DNA profile belonging to a man convicted of a felony.  This similarity indicated the convicted man was a close relative of the Grim Sleeper.

Using circumstantial information, the police identified Lonnie David Franklin Jr., the convicted man’s father, as the relative most likely to be the Grim Sleeper (details in the LA Times excerpt below).  Based on this lead, police collected so-called “abandoned” DNA from a piece of pizza Franklin discarded.  Franklin’s abandoned DNA matched the Grim Sleeper’s crime scene DNA, and Franklin was arrested.

Both familial searching and collecting abandoned DNA are controversial investigatory techniques.  Several states allow analysts to disclose partial DNA matches (which indicate a potential relative) found inadvertently while searching for an exact match. California, however, has an explicit policy allowing intentional searches for family members and additional genotyping of the stored DNA samples to increase the accuracy of the familial search.

The LA Times story noted that the suspect had been convicted four times of criminal offenses, two misdemeanors and two charges of felony possession of stolen property, which may lead some to wonder why Franklin’s DNA was not already included in the state and CODIS databases.  The last of his felony convictions occurred in 2003 and resulted in 270 days in prison. California was collecting DNA in 2003 but only from people convicted of certain serious felony offenses; possession of stolen property was not one of these qualifying offenses  (WL subscription required for 2003 version of statute).  The law was amended in November 2004 to expand DNA collection to persons convicted of any felony who are incarcerated, on parole, or on probation, to be implemented “as soon as administratively practicable.” His incarceration ended a few months before the law changed (and perhaps longer before it would have been implemented).

L.A. Times:

For well over two decades, the killer had eluded police. His victims, most of them prostitutes in South Los Angeles, had lived on the margins of society, and their deaths left few useful clues aside from the DNA of the man who had sexually assaulted them in the moments before their deaths.

A sweep of state prisons in 2008 failed to come up with the killer or anyone related to him. Then, last Wednesday, startling news came to the LAPD: A second “familial search” of prisons had come up with a convict whose DNA indicated that he was a close relative of the serial killer suspected of killing at least 10 women.

Working through the Fourth of July weekend, LAPD detectives drew up a family tree of the prisoner, then began analyzing all the men on it. Were they the right age? Did they live near the murder scenes? Was there anything in their background to explain why the serial killer had apparently stopped killing for 13 years, then resumed in 2003?

From that painstaking process, according to LAPD officials who requested anonymity, the prisoner’s father emerged as a likely suspect. An undercover team was sent to follow him; they retrieved a discarded slice of pizza to analyze his DNA. On Tuesday, they confirmed that it matched the DNA of the suspect in the killings.”  Read more…

– Kelly Lowenberg (h/t Hank Greely)

2 Responses to Familial DNA Searching and Abandoned DNA Identify the Grim Sleeper Serial Killer
  1. Thanks for the post, Kelly! I’ve been just waiting for this to happen. Denver may have led the charge on this practice, but I guess California just couldn’t stand to be behind on something.
    As much as I’m opposed to this practice (which is generally very much so), if there were ever a way to justify familial searching, this case is probably it.

    It looks from the charges like the DA’s office is planning to seek the death penalty. Any word?
    I’m also curious what you think about the abandoned DNA. You put it in quotes. . . is there a fight there?

  2. For those interested in familial searching in this case, KQED radio (a San Francisco NPR station) did an hour-segment on this topic today at 10:00 am, featuring Erin Murphy (of Boalt, but on her way to take up a position at NYU this fall) and me. It was fun and I thought pretty informative. Here’s a link to the audio recording:


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