Complex sentence: Since 1991, she has headed the archaeological mission from the Louvre Museum at Saqqara, during which time she excavated and wrote a book on the Tomb of Akhethetep, paying particular attention to its reliefs.
Split into simpler sentences: Since 1991, she has headed the archaeological mission from the Louvre Museum at Saqqara. During which time she excavated and wrote a book on the Tomb of Akhethetep, paying particular attention to its reliefs.