Grand jury spurs Russia investigation

Angry Trump says Moscow ties at 'very dangerous low'

WASHINGTON - Special counsel Robert Mueller is using a grand jury in Washington as part of an investigation into alleged coordination between the Donald Trump campaign and Russia, a source familiar with the probe said on Thursday.

The use of a grand jury, a standard prosecution tool in criminal investigations, suggests that Mueller and his team of investigators are likely to hear from witnesses and demand documents in the coming weeks and months.