Here’s a sentence (slightly disguised) that I read in a recent report:

Wilson is accused of killing Johnson, his girlfriend and a teammate.

How many people? It could have been two: a girlfriend named Johnson and a teammate. Or perhaps it was three: Johnson, a girlfriend, and a teammate. Or it could even have been one: a girlfriend and teammate whose name was Johnson.

But if you add another comma, it’s still confusing:

Wilson is accused of killing Johnson, his girlfriend, and a teammate.

There could still have been two victims – a girlfriend named Johnson and a teammate. Or there could have been three: Johnson, along with his girlfriend and another person who was a teammate.

And notice that his girlfriend could refer to either Wilson or Johnson.

This sentence illustrates why it’s so important to teach officers to think rather than simply have them memorize rules and complete workbook exercises.

Here are two suggested revisions that clearly state how many victims there were:

Wilson is accused of killing both Johnson’s girlfriend and a teammate.  BETTER

Wilson is accused of killing three people: Johnson, Johnson’s girlfriend, and a teammate.  BETTER

Bottom line: Don’t fool yourself into thinking that you can solve any sentence problem with a punctuation mark. Sometimes you’ll need to cross out a sentence and rewrite it. Often I find that I need to break one long sentence into two shorter ones – there’s no other way to make my point clear.

Here’s a final tip: always reread your report before you submit it. If possible, ask another person to read it as well. Something that’s perfectly clear to you might be confusing to someone else who wasn’t there when the event happened. Language can be slippery!