Why Is Rape Kit Testing So Expensive?

How Cheap Gene Sequencing Technology Should Be a Game Changer

During the O.J. Simpson trial, prosecutor Marcia Clark had the unenviable task of describing DNA profiling to jurors. She tried valiantly to explain the incredible precision of restriction fragment length polymorphism tests and how they pointed to Simpson. Ultimately, jurors were more convinced by the size of a glove than with statistics and DNA.

Luckily, after many years and thousands of CSI reruns, the public is much better educated about the power of genomics. Just last year, decades-old DNA evidence and the publicly available GEDmatch database were used to find the Golden State Killer. More and more crimes seem close to being solved using the same public data and DNA.

This raises an obvious question. If cheap and ubiquitous DNA testing can catch killers and rapists, then why are so many rape kits still sitting untested? It’s well known that many violent crimes are perpetrated by serial offenders. Failing to use evidence that could catch them seems insane.

In the 90s, there may have been good reasons not to prioritize rape kit testing. In 2019 there are no excuses. Let’s take a look at why the rape kit backlog exists and why it must be addressed now.

Why the Backlog?

The nonprofit program End The Backlog lists 5 reasons that sexual assualt kits are left untested. These are:

  1. Lack of protcols for rape kit testing
  2. Knowledge gaps and lack of training
  3. Whether the identity of the perpetrator is known
  4. Lack of resources
  5. Outdated lab policies

Of these, reasons 1,2 and 5 come down to awareness and training — things that can and must be addressed. In fact, proposals like the one from Democratic candidate Kamala Harris do a good job of raising awareness of rape kits and the need to process them. What these proposals also do is promise millions of dollars to address the backlog. This suggests that the main reason so many kits haven’t been processed is issue number 4, a lack of resources.

If this is the case, then there is no need to debate rape kit testing any further. While some sources estimate that it costs $1000 to $1500 to test a single rape kit, the price of doing so in 2019 is likely much lower. Amazing advancements in DNA sequencing mean that the resources required to bring justice to rape victims is lower than ever before.

DNA Testing Costs are Going Down

Although some money is required to properly handle DNA samples in a forensic setting, much of the cost of rape kit testing is in gene sequencing. Luckily the cost of gene sequencing has been falling for years.

When the Human Genome project was completed in 2003, it cost over $50 million dollars to sequence a full human genome (~3 billion basepairs of DNA). Today, the cost of the same sequencing is only around 1000 US dollars.


The above data reflects the cost of full genome sequencing. For forensic purposes, a much smaller subset of DNA can be sequenced at a much lower cost. After all, there’s a reason that popular DNA testing services (like the one used to catch the Golden State killer) are as little as $50. They only test a few million base pairs.

Although we shouldn’t count on companies like 23andMe to process DNA for police departments, public labs like this one quote only $60 per sample when doing bulk gene sequencing. If police departments pooled their resources to test rape kits at these DNA labs, they could share costs and make rape-kit testing much more economical.

Of course, cost isn’t the only reason that rape kit testing is a no brainer. Advances in big data and machine learning mean that these kits are much more likely to lead to arrests.

Big Data Can Catch Criminals

In the early 90s, when O.J. was on trial, you needed to have a perpetrator in custody to get reference DNA samples. Now there’s no need for that. Perpetrators can be completely unknown to police and still be found with modern statistical methods.

For instance, The Federal Combined DNA Index System (or CODIS) is a store of DNA data from millions of known offenders, including records from crime scenes across the country. Whenever a rape kit is tested it can easily be compared to the records in this database. In fact, one such study from 2016 found that when 900 sexual assault kits were tested, there were 256 matches to this CODIS database. That’s an amazing 28% hit rate from this database alone.

But even this amazing finding understates the power of DNA testing. As the Golden State Killer case proved, DNA connections are everywhere. In that case, the DNA of the killer’s relatives was publicly available, and these matches were enough to point investigators in the right direction. Some researchers estimate that they can identify 60% of white Americans using family DNA connections.

As millions more sign up to services like 23andMe and Ancestry.com, it’s only a matter of time before federal law allows for criminal searches against these databases. Even without federal legislation, companies like FamilyTreeDNA are asking customers to opt in to sharing their data with law enforcement. This kind of data sharing would make it possible to solve thousands of cases.

We’re already well on the road to this future. DNA analysis tools designed to aid law enforcement are currently in development by multiple companies including Othram. With these tools, it might someday be impossible to get away with crimes where DNA evidence is obtained.

Final Thoughts

It is estimated that there are somewhere between 200,000 and 400,000 untested rape kits sitting in U.S. police departments. This unacceptable state of affairs persists despite the efforts of nonprofit organizations like RAINN, and the Joyful Heart Foundation.

While lack of funding was a valid reasons not to test kits in the 90s and 00s, it is no longer valid today. The costs of DNA sequencing continues to fall, and DNA data analysis gets more sophisticated every year. With these advancements, there is no longer any good reason not to end the rape kit backlong and to bring some measure of peace to rape victims nationwide.

Married engineer in San Francisco. Interested in words, networks, and human abstractions. Opinions expressed are solely my own.

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