[susan53]

I'm not completely sure what you mean here. It doesn't "refer to" anything. Was your question really "What does it mean?" ? If so, it means to adopt an attitude of potential suspicion or doubt towards something (in our case, the suspect). In other words that they were not necessarily going to believe what they said.

As I said - the verb to question automatically involves this type of attitude. Even if the police are questioning a witness, or even a victim, they have to allow for the possibility that the person is mistaken (witnesses aren't always reliable) or even lying. Just saying : The police questioned the suspect/witness/victim about XXX inevitably suggests that they were open to the possibility that what they heard was not true.

[fface]

Hi susan,

Do 'close in on someone' and 'zero in on someone' mean the same thing here in the example above? The phrase 'zero in on...' also appears in the video at 26:59.

Many thanks.

[susan53]

In the video, yes it's the same.

You can "zero in on" someone or something, meaning to focus/concentrate on, or investigate closely. So eg

1. In the Africa bombings manhunt both magazines ZERO IN ON Osama Bin Laden the technosavvy multimillionaire Saudi exile living in Afghanistan (see here)

2. Instead Chatterbox ZEROED IN ON the two years when Gore cast considerably more votes considered anti environment by the LCV than he did in other years (see here)

3. The Wall Street Journal's The Outlook column ZEROES IN ON the closest thing to a storm cloud in the current economic forecast - the stunning erosion of lending standards (see here)