Serial Murder, computer forensics, FBI?

Anonymouse said:

My MC detective is receiving messages directed at him through electronic means (public forum; it's somewhat ambiguous that the messages are directed *at* him, except they contain information that only someone at particular scenes would know). He's slightly paranoid and has some reasons why he doesn't want to go to his supervisor with the info quite yet. I'd personally prefer to see the messages going to his personal email at work. It's not that difficult to figure this out as many places aren't too swift at setting these up. If it's a public forum, other members of the police department are likely to see it.

One of his cases has just been closed as an accidental death (via drowning). His open case is *also* a drowning where there were signs of a struggle, but as of yet no clear suspect. He's beginning to think that the cases are linked and he may be looking at a serial killer. You're going to have a hard time with the first drowning. For a case to be ruled by the medical examiner as "accidental drowning," there are certain criteria that have to be met. In other words, you need evidence that the drowning was caused by an accident.

1) At what point in an investigation would the local authorities bring in the FBI on a case like this? When the police officer is able to convince his department that he has a reasonable suspicion.
2) Are there databases available that would allow *him*, personally, to search for similar cases in neighboring jurisdictions, or is that more of an FBI kind of thing?
3) If and when he does show someone the messages (they are anonymously written from various public internet terminals around the city), is there an easy way of tracing the messages back to individual computers? (I'm actually hoping not, though I'm not sure it would matter that much in the end). You can go from easy to find to next to impossible to find. IP masking is possible with minimum skill and makes this a bit difficult.

Apologies if these are simple questions to answer. If there are good resources (procedural manuals, etc.) that a brand-new mystery writer can read to grasp the absolute basics of police procedure and such, please feel free to lead me to those sources. I'm willing to read and learn; I'm just having

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Jim Clark-Dawe

In addition to the above, he can likely try VICAP to see if he can get a hit.

Basically you have a victim who fell into the river. First problem is most times when you fall, you don't fall into water. So why is she near water? Addicts don't go near water for swimming, fishing, or enjoying the view. However, I will also mention that many of the homeless in my part of the country camp along rivers, so that would be a possible scenario. The homeless frequently use the river for various bodily functions, such as a toilet and bath.

Most accidental drownings are a result of boating and swimming. In other words, the person has a reason for being in the water.

Next is that, absent a secondary cause, you fall into the water, even if the banks are fairly steep, you can usually get out on your own. This is true even if you're not a swimmer. Here we look at clothing (heavy clothing that causes you to sink), swimming ability, injuries, and whether you're under the influence of any substance. Nearly all accidental drownings not related to boating and swimming will have at least one of these factors and frequently several.

For a struggle, we're looking for two different things. One is whether there is terrain damage. Scuff marks, broken branches, so on and so forth, will indicate a physical struggle. The second is bruising on the body. River drownings will indicate some damage after death, as the body floats downstream hitting rocks and branches. A competent examination will be able to discount this damage. But in a struggle, bodies will frequently have bruises, especially on the upper arms and torso. Bruises on the legs are most likely to occur during the drowning. Head bruises can be a bit harder to figure out.

The medical examiner pronounces cause of death to a reasonable degree of medical certainty. Here we have two different facts that the medical examiner needs to determine -- what is the cause of death, and then why did it happen. Drowning is relatively easy to determine in an autopsy. So the cause of death would be listed. Why it happened is the hard part. So the result would be "death by drowning, cause indeterminant." (Phrased somewhat differently by different medical examiners.) The medical examiner might then list the probable cause, for instance, "death by drowning, cause indeterminant, probably accidental."

Jim Clark-Dawe