Historical clue formulations

• Get more complex, as a mystery — 2023-06-15
• Intensify — 2022-03-23
• Become more complicated, say — 2022-01-16
• Intensify — 2021-10-02
• Grow, as sympathies — 2018-01-20
• Intensify — 2017-01-04
• Dredge, say — 2013-12-18
• Become more intense — 2013-05-13
• Get worse, as losses — 2012-10-22
• Intensify — 2009-12-13
• Excavate — 2004-04-23
• Dredge — 2001-12-19
• Grow more intense — 1996-10-19
• Become more serious — 1996-09-27
• Excavate — 1996-04-13
• Intensify — 1995-02-05