<p>Since my answer at the <a href="https://anime.stackexchange.com/a/56701/4484">linked question</a> answers this question as well, I will only copy it in a quote:</p>
<blockquote>
<p>After handing over the Death Note to Rem in the plan to free Misa out
Light says (chapter 54):</p>
<p><a href="https://i.sstatic.net/awxBw.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/awxBw.png" alt="enter image description here" /></a></p>
<p>In other words, he <strong>tore the pages</strong> out and checked there's <strong>none
of the fingerprints or his handwriting</strong>, so it's no surprise that L
didn't check out the handwriting since there weren't any other names
written beside Higuchi's.</p>
<p>All though it didn't mentioned in the anime, <strong>it's unthinkable that
Light would missing do such an obvious thing.</strong></p>
</blockquote>
<p>And as for <em>hair</em> and <em>DNA</em> as mentioned in the question, I think it's obviously.</p>

CC BY-SA 4.0
2020-10-12T08:25:12.727Z
I find it weird that Light could somehow completely wipe out all traces of physical evidence, but eh at least it was mentioned. Thanks!
BCLC
CC BY-SA 4.0
2020-10-12T09:44:11.897Z
it's light we are talking about, the one who even were ready to burn all his desk and family so the Death Note won't be discovered, so he won't be able to remove all his traces from the Death Note?
USerNAme
CC BY-SA 4.0
2021-02-08T04:42:49.653Z
USerNAme, eh, idk. it's so hard for people like dexter, but apparently it's a piece of cake (or potato chip) for light. i just view it as part of suspension of disbelief or whatchamacallit
BCLC
CC BY-SA 4.0
2021-02-15T12:47:20.083Z
@BCLC we have official source, why to think too hard on this?
USerNAme
CC BY-SA 4.0
2021-12-11T19:34:13.260Z
USerNAme, i don't really buy it, but i'm not really thinking hard as to whether i should really buy it or not
BCLC
CC BY-SA 4.0
2021-12-11T19:47:41.153Z
@BCLC you compared light to dexter. you should remember that dexter killed by hand with blood and all. light just had to clean the notebook from hair and stuff. lol
USerNAme
CC BY-SA 4.0
2022-01-23T09:05:34.100Z
'just' ? hair and fingerprints are really big deals i believe.
BCLC
CC BY-SA 4.0
2020-10-11T12:54:50.740Z
2020-10-12T09:42:02.357Z
2020-10-12T09:42:02.357Z
USerNAme
<p>When the Kira Task Force recovered the Death Note from <a href="http://deathnote.wikia.com/wiki/Kyosuke_Higuchi" rel="nofollow noreferrer">Kyosuke Higuchi</a> there is 2 things which contaminated any DNA evidence on the Death Note:</p>

<ol>
<li>The Kira Task Force touched the Death Note to see Rem</li>
<li>Light was holding onto the Death Note as part of his plan to reclaim ownership (when his memories returned)</li>
</ol>

<p>To my knowledge there is no way to tell "when" fingerprints or DNA first made contact with an object being tested as such any of Light's DNA found on the Death Note can easily be explained by his interactions with it when the Death Note was recovered.</p>

<p>Remember that the idea was to capture Kira and convict him in a court of law and DNA on the Death Note would be inadmissible due to how it was handled. This is why the police tend to block of crime scenes ensure that the proper <a href="https://en.wikipedia.org/wiki/Chain_of_custody" rel="nofollow noreferrer">Chain of Evidence</a> is met. In some cop shows there are times that, when a seal is broken or multiple undocumented people handled a particular piece of evidence, it can't be used in court. </p>

<p>Even if Light didn't touch the Death Note when it was recovered and L found Light's DNA on it, suspecting Light again after the 13-day rule seemed to show his innocence would not help L since up until now Light had been very cooperative in aiding the Task Force and they were all on good terms. He would first need to prove to the rest of the Task Force/Police that the 13-day rule is fake  thus returning to what I have explained <a href="https://anime.stackexchange.com/a/26617/1587">here</a> and then rule out any other way Light's DNA could have gotten onto the Death Note after it's recovery.</p>

CC BY-SA 3.0
2016-03-07T19:00:29.547Z
That about sums it up probably. Though I honestly don't think they would've found much by way of DNA even without being contaminated. Light knows about that and is anal about it. The switching of notes happens with him using a handkerchief to keep his DNA off it and I wouldn't doubt he wiped them both clean beforehand to clear him and Misa on the chance that they did try forensics testing.
Lenora
CC BY-SA 3.0
2015-10-14T23:42:52.483Z
2016-03-07T09:24:14.143Z
2017-04-13T12:54:49.117Z
Memor-X
<p>Related to this: <a href="https://anime.stackexchange.com/questions/20584/death-note-handwriting-check">Death note handwriting check</a></p>

<p>A lot of DNA must have rubbed off on the Death Notes. Unless the Death Note has a rule about fingerprints or DNA, I don't see how this isn't a plothole.</p>

CC BY-SA 3.0
2015-10-14T22:41:36.880Z
@ton.yeung What? I think that in general books can examined for DNA. I'm guessing the Death Note has a rule for such things. If not, this seems to be a plothole.
BCLC
CC BY-SA 3.0
2015-10-14T22:45:45.477Z
@ton.yeung Oh drat. I guess forensic knowledge is needed. You mean to say just because you press your finger on a book doesn't mean that your fingerprint will be there? I see in a lot of movies and series that people shine some fancy flashlights on walls or guns and then can see fingerprints. So that's just artistic license?
BCLC
CC BY-SA 3.0
2015-10-14T22:46:27.850Z
i am quite sure the entire task force touched the Death Note to see Rem. unless they did the testing before then there would be (to my knowledge) no way to check if Light had touched it previously as his fingerprints and DNA could just have been from when the task force touched it
Memor-X
<death-note>
Why didn't L check for fingerprints or hair?
# Why didn't L check for fingerprints or hair?
Posted by: username_0 on 2015-10-14
Related to this: [Death note handwriting check](https://anime.stackexchange.com/questions/20584/death-note-handwriting-check)

A lot of DNA must have rubbed off on the Death Notes. Unless the Death Note has a rule about fingerprints or DNA, I don't see how this isn't a plothole.
**Tags:** death-note
> **Comments:**
> **username_0**: @ton.yeung What? I think that in general books can examined for DNA. I'm guessing the Death Note has a rule for such things. If not, this seems to be a plothole.  
> **username_0**: @ton.yeung Oh drat. I guess forensic knowledge is needed. You mean to say just because you press your finger on a book doesn't mean that your fingerprint will be there? I see in a lot of movies and series that people shine some fancy flashlights on walls or guns and then can see fingerprints. So that's just artistic license?  
> **username_1**: i am quite sure the entire task force touched the Death Note to see Rem. unless they did the testing before then there would be (to my knowledge) no way to check if Light had touched it previously as his fingerprints and DNA could just have been from when the task force touched it  
---
## 2 answers
### Answer by username_2 on 2020-10-11. Score: 1 | Accepted answer
Since my answer at the [linked question](https://anime.stackexchange.com/a/56701/4484) answers this question as well, I will only copy it in a quote:

> After handing over the Death Note to Rem in the plan to free Misa out
> Light says (chapter 54):
>
> [![enter image description here](https://i.sstatic.net/awxBw.png)](https://i.sstatic.net/awxBw.png)
>
> In other words, he **tore the pages** out and checked there's **none
> of the fingerprints or his handwriting**, so it's no surprise that L
> didn't check out the handwriting since there weren't any other names
> written beside Higuchi's.
>
> All though it didn't mentioned in the anime, **it's unthinkable that
> Light would missing do such an obvious thing.**

And as for *hair* and *DNA* as mentioned in the question, I think it's obviously.
> **Comments:**
> **username_0** (2020-10-12): I find it weird that Light could somehow completely wipe out all traces of physical evidence, but eh at least it was mentioned. Thanks!  
> **username_2** (2020-10-12): it's light we are talking about, the one who even were ready to burn all his desk and family so the Death Note won't be discovered, so he won't be able to remove all his traces from the Death Note?  
> **username_0** (2021-02-08): USerNAme, eh, idk. it's so hard for people like dexter, but apparently it's a piece of cake (or potato chip) for light. i just view it as part of suspension of disbelief or whatchamacallit  
> **username_2** (2021-02-15): @BCLC we have official source, why to think too hard on this?  
> **username_0** (2021-12-11): USerNAme, i don't really buy it, but i'm not really thinking hard as to whether i should really buy it or not  
> **username_2** (2021-12-11): @BCLC you compared light to dexter. you should remember that dexter killed by hand with blood and all. light just had to clean the notebook from hair and stuff. lol  
> **username_0** (2022-01-23): 'just' ? hair and fingerprints are really big deals i believe.  
---
### Answer by username_1 on 2015-10-14. Score: 6
When the Kira Task Force recovered the Death Note from [Kyosuke Higuchi](http://deathnote.wikia.com/wiki/Kyosuke_Higuchi) there is 2 things which contaminated any DNA evidence on the Death Note:

1. The Kira Task Force touched the Death Note to see Rem
2. Light was holding onto the Death Note as part of his plan to reclaim ownership (when his memories returned)

To my knowledge there is no way to tell "when" fingerprints or DNA first made contact with an object being tested as such any of Light's DNA found on the Death Note can easily be explained by his interactions with it when the Death Note was recovered.

Remember that the idea was to capture Kira and convict him in a court of law and DNA on the Death Note would be inadmissible due to how it was handled. This is why the police tend to block of crime scenes ensure that the proper [Chain of Evidence](https://en.wikipedia.org/wiki/Chain_of_custody) is met. In some cop shows there are times that, when a seal is broken or multiple undocumented people handled a particular piece of evidence, it can't be used in court.

Even if Light didn't touch the Death Note when it was recovered and L found Light's DNA on it, suspecting Light again after the 13-day rule seemed to show his innocence would not help L since up until now Light had been very cooperative in aiding the Task Force and they were all on good terms. He would first need to prove to the rest of the Task Force/Police that the 13-day rule is fake thus returning to what I have explained [here](https://anime.stackexchange.com/a/26617/1587) and then rule out any other way Light's DNA could have gotten onto the Death Note after it's recovery.
> **Comments:**
> **username_3** (2016-03-07): That about sums it up probably. Though I honestly don't think they would've found much by way of DNA even without being contaminated. Light knows about that and is anal about it. The switching of notes happens with him using a handkerchief to keep his DNA off it and I wouldn't doubt he wiped them both clean beforehand to clear him and Misa on the chance that they did try forensics testing.  
---
