ascertain

Russian legal experts say the true scale of the problem is hard to ascertain.

Mr Lawson said the pioneering work had even ascertained where the people, who were buried between the 12th Century and 1560, were born.

She named seven men, whose whereabouts could "not be ascertained", as having committed or being complicit in the murder.

Fire service officials have not ascertained which of the two buildings caught fire first.

Speaking at a news conference on Monday, officials said the incident was a "targeted act of violence", but said they had not yet ascertained Sanford's motive.