Historical clue formulations

• Shadow, e.g. — 2023-09-13
• Secretly surveil — 2023-05-07
• Secretly watch — 2022-01-22
• Watch surreptitiously — 2021-01-26
• Watch surreptitiously — 2019-10-24
• Shadow, e.g. — 2015-10-03
• Observe secretly — 2012-02-07
• Watch furtively — 2010-06-09
• Watch furtively — 2008-11-30
• Watch through binoculars, say — 2008-08-04
• Observe furtively — 2007-04-01
• Secretly watch — 2006-06-04
• Observe furtively — 2005-12-12
• Secretly watch — 2003-10-03
• Watch slyly — 2002-03-29
• Watch secretly — 1999-12-20
• Secretly watch — 1998-01-21