2026年2月20日 / 美国东部时间下午6:44 / CBS新闻
亚利桑那州南希·格思里案的调查人员已转向一种名为遗传谱系学的调查技术，试图充分利用在寻找《今日》主持人萨凡娜·格思里母亲的过程中收集到的DNA证据。
这一手段在过去十年中成功破解了多起著名案件，包括在加利福尼亚州确认了所谓的”金州杀手”身份——该罪犯逃脱当局追捕长达40多年，以及四名爱达荷州大学生被残忍杀害案的真凶。
84岁的南希·格思里被认为在深夜被强行带离图森住所近三周后，当局仍未锁定嫌疑人或相关人员。皮马县警长部门本周宣布，萨凡娜·格思里及其两位兄弟姐妹和他们的配偶已被排除嫌疑。
警长部门还表示，在距离南希·格思里住所约2英里处发现的一副手套上的DNA图谱，与联邦调查局（FBI）维护的全国DNA索引系统（CoDIS）中的任何条目均不匹配。该数据库包含有犯罪前科人员提供的DNA样本。
此外，警长部门称手套上的DNA与南希·格思里住所发现的其他DNA证据不匹配。调查人员在其住所收集到的DNA既不属于格思里本人，也不属于与其亲密接触者，目前正在努力确定DNA来源。部门周五表示，调查中恢复的生物证据分析工作正在进行，此类过程可能耗时较长。
这是2026年2月15日拍摄的空中视角，皮马县警长部门一名警官在亚利桑那州图森市南希·格思里住所外守卫。布兰登·贝尔/盖蒂图片社
警方指出，调查人员正在研究使用遗传谱系学的调查选项，以核查匹配结果。一名联邦执法部门消息人士告诉CBS新闻，调查人员也将核查商业DNA数据库——这些数据库与CoDIS相互独立。
纽约警察局前副警长伊曼纽尔·卡特拉卡基斯在纽约警察局法医调查部门工作25年并担任指挥官，他向CBS新闻表示，遗传谱系学本质上是在联邦或州数据库中无直接或部分匹配结果时，在收集证据并检索CoDIS后，将DNA样本与人员进行匹配的最终手段。
“如果作案者有亲属在数据库中被定罪，就可以围绕这一亲属构建家族谱系树，”卡特拉卡基斯说，”这是一种广泛撒网的策略，寻找表亲关系。”
这一策略此前已被成功应用。
在爱达荷州，布莱恩·科伯格于2022年在四名大学生家中凌晨实施谋杀后，去年认罪并被判处四个终身监禁。调查人员通过从其中一名受害者尸体附近发现的刀鞘纽扣上提取的DNA，成功将其与凶手关联。
检察官称，联邦调查局利用系谱网站，根据犯罪现场DNA图谱构建遗传亲属的家族树，进而确定科伯格为嫌疑人。调查人员搜查了科伯格父母位于宾夕法尼亚州的家中垃圾，发现了一根棉签，经确定其DNA来自科伯格父亲——该棉签被认为与爱达荷州家中发现的DNA有关联。
2025年7月23日，布莱恩·科伯格在爱达荷州博伊西市的量刑听证会上出庭。美联社/凯尔·格林，联合记者
在加利福尼亚州，针对所谓”金州杀手”长达数十年的追捕（该杀手实施了13起谋杀和数十起强奸），最终在2018年逮捕了一名70多岁的退休警官——起因是其DNA样本被提交至一个受系谱爱好者欢迎的公共数据库。
法庭文件显示，该样本是在1980年双尸案后收集的，但直到21世纪才与执法系统中的任何记录匹配。在转向公共数据库后，调查人员最终锁定了约瑟夫·迪安杰洛。他于2018年因调查人员从其垃圾中获取带有DNA的组织而被捕。现年80岁的迪安杰洛于2020年认罪，目前在狱中服多个终身监禁。
2020年8月20日，约瑟夫·詹姆斯·迪安杰洛在加利福尼亚州萨克拉门托的受害者影响陈述法庭上就座。圣地亚哥·梅贾/旧金山纪事报通过美联社，联合记者
南加州私人法医DNA实验室Pure Gold Forensics的实验室主任苏珊娜·瑞安告诉CBS新闻，当调查人员转向遗传谱系学分析时，必须保留足够的DNA样本以进行额外检测。
“有时原始实验室必须使用全部样本进行传统检测，才能尝试获得结果，”她在电子邮件中表示。
理想的DNA样本应具有单一来源的遗传图谱，如血迹或精液样本。瑞安解释道，但实验室也可处理含有两个来源的样本，只要大部分样本来自潜在作案者。
“实验室可以处理混合样本，例如80%来自作案者A和20%来自B，只要潜在作案者是80%的成分，”瑞安说，”如果情况相反，他们通常无法对这种类型的混合样本进行后续系谱研究。”
在刑事调查中使用系谱数据库引发了疑问：上传DNA图谱的用户是否完全了解其数据可能被如何使用。
允许用户通过DNA数据寻找亲属的FamilyTreeDNA告诉CBS新闻，该公司不直接与执法部门合作开展法医遗传谱系学案件。该公司表示，相关工作由使用基于同意的数据库的独立第三方合作伙伴进行。
“在FamilyTreeDNA参与调查性遗传谱系学匹配是严格自愿的，且仅通过选择加入方式，”该公司在声明中称，”我们在所有运营方面都将客户隐私、数据安全和道德使用放在首位。”
CBS新闻还联系了其他几家知名商业DNA数据库公司以获取回应。
帕特·米尔顿和格蕾丝·萨缪尔森对本文报道有贡献。
Investigators in Nancy Guthrie case turn to genetic genealogy for DNA leads, a tactic that’s cracked big cases before
February 20, 2026 / 6:44 PM EST / CBS News
Investigators in the Nancy Guthrie case in Arizona have turned to an investigative technique called genetic genealogy as they try to make the most of DNA evidence that’s been collected during the search for the mother of “Today” show co-host Savannah Guthrie.
The process has been used to crack some notable cases in the past decade, including identifying the so-called Golden State Killer in California who’d eluded authorities for over 40 years and the man behind the high-profile killings of four Idaho college students.
Nearly three weeks after Nancy Guthrie, 84, was believed to have been forcibly taken from her Tucson home in the middle of the night, authorities haven’t named a suspect or a person of interest in the case. The Pima County Sheriff’s Department announced this week that Savannah Guthrie, her two siblings and their spouses have been cleared as suspects.
The sheriff’s department has also said that a DNA profile from a set of gloves found about 2 miles from Nancy Guthrie’s house didn’t match any entries in the national database maintained by the FBI known as the Combined DNA Index System, or CoDIS. The database contains DNA profiles of individuals with a previous arrest for certain crimes who had supplied a DNA sample.
The sheriff’s department also said that the DNA profile from the gloves didn’t match other DNA evidence from Nancy Guthrie’s property. The department has said DNA was collected at the property that isn’t from Guthrie or those in close contact with her, and that investigators were working to identify who it came from. The department said Friday that DNA analysis was underway on biological evidence recovered during the investigation and that the process can be lengthy.
In an aerial view, a Pima County sheriff’s deputy keeps guard outside of Nancy Guthrie’s residence on Feb. 15, 2026, in Tucson, Arizona. Brandon Bell/Getty Images
The department noted that investigators were looking into investigative genetic genealogy options to check for matches. A federal law enforcement source told CBS News investigators would also be checking commercial DNA databases, which are separate from CoDIS.
Emanuel Katranakis, a former deputy chief with the New York Police Department who spent 25 years in the NYPD’s Forensics Investigations Division and was its commanding officer, told CBS News that genetic genealogy is essentially the final effort to match a DNA sample to a person after collecting the evidence and searching in CoDIS, if there is no direct or partial match in the federal or state databases.
“If this perpetrator has a relative that is a convicted offender in the database, you build a family tree around it,” Katranakis said. He also said, “You’re throwing a wide net, you’re looking for cousins.”
It’s a strategy that has worked before.
In Idaho, Bryan Kohberger is serving four life sentences after pleading guilty last year to killing four college students in the early morning hours in their home in 2022. Investigators were able to tie him to the killings using DNA retrieved from the button snap of a knife sheath that was left near one of the slain students’ bodies.
The FBI used genealogy sites to build family trees of genetic relatives using the crime scene DNA profile, and from there identified Kohberger as a possible suspect, prosecutors said. Investigators searched through garbage from the Pennsylvania home of Kohberger’s parents and recovered a Q-tip that was determined to come from the father of the person whose DNA was found at the Idaho home.
Bryan Kohberger appears at his sentencing hearing July 23, 2025, in Boise, Idaho. AP Photo/Kyle Green, Pool
In California, the decadeslong pursuit of the so-called Golden State Killer, who was behind 13 killings and dozens of rapes, led to the 2018 arrest of a retired police officer in his 70s after a DNA sample was submitted to a public database popular with genealogy enthusiasts.
The sample was collected after a double murder in 1980 but didn’t match with anything in law enforcement’s systems until the 21st century, according to court documents. After turning to the public database, investigators ultimately landed on Joseph DeAngelo. He was arrested in 2018 after investigators obtained a tissue from his trash that had his DNA. DeAngelo, now 80, pleaded guilty in 2020 and is serving multiple life sentences.
Joseph James DeAngelo sits in court during victim impact statements Aug. 20, 2020, in Sacramento, California. Santiago Mejia/San Francisco Chronicle via AP, Pool
Suzanna Ryan, laboratory director at private forensic DNA lab Pure Gold Forensics in Southern California, told CBS News that when investigators turn to genetic genealogy, there has to be enough of a DNA sample left to undergo additional analysis.
“Sometimes the original lab has to use all of the sample for traditional testing in order to even attempt to obtain a result,” she said in an email.
An ideal DNA sample would have a single source profile, like a blood stain or a semen sample, Ryan said. However, labs can also work with samples that have two contributors as long as most of the sample is from a potential perpetrator.
“The labs could work with a mixture of, let’s say 80% contributor ‘A’ to 20% contributor ‘B’ as long as the potential perpetrator is the 80% component,” Ryan said. “If it’s the other way around, they usually can’t do much with that type of mixture in terms of the downstream genealogical research.”
The use of genealogical databases in criminal investigations has raised questions about whether people who upload their DNA profiles are fully aware of how they might be used.
FamilyTreeDNA, which allows users to use their DNA data to find relatives, told CBS News it doesn’t work directly with law enforcement on forensic genetic genealogy cases. The company said related work is carried out through an independent third-party partner that uses a consent-based database.
“Participation in investigative genetic genealogy matching at FamilyTreeDNA is strictly voluntary and opt-in only,” the company said in a statement. “We place the highest priority on customer privacy, data security, and ethical use in all aspects of our operations.”
CBS News has also reached out to several other popular commercial DNA database companies for their responses.
Pat Milton and Grace Samuelson contributed to this report.
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