A few months ago I called up a reporting hotline to report an incident.
Now it wasn't an in-person law enforcement encounter, and I wasn't the suspect but the victim. The agent on the phone was only tasked with taking down the report and forwarding it.
She listened to my narrative and took down the facts. Then she began to relate it back to me, and at every turn, she gave me the wrong details and altered the story.
So I found myself correcting her again and again and ironing out the actual facts so she had them right. And I came to realize that her mistakes were probably not accidents, but she was intentionally prompting me to reinforce the same narrative as I'd stated it, because if someone is lying, fabricating, or embellishing the truth, they won't be able to repeatedly insist on the facts as retained in their memory.
Conversely, I've had interactions with authority figures, who seem to intentionally misspeak as a test. They want to see if I will challenge the veracity of what they said, or if I can accept that their knowledge counts for more, and perhaps I shouldn't openly question them for every trivial matter.
So if the police succeed in implanting false memories, then maybe someone just had a shitty memory to begin with. If someone's involved in a crime, even as an eyewitness, it's important to work with their perspective, because testimonies consist of a lot of subjective information, and different people have different capacities for recall, so if you ask 3 eyewitnesses what happened, you may get 3 different but true stories, then you reconcile them. Just ask Matthew, Mark, and Luke.