BEIJING — The frothy contemporary-art scene here has lost some of its ebullience in the three and a half months since a German art handler and a Chinese associate were detained on charges that they undervalued imported art to avoid customs duties.

Gallery openings are a bit more subdued, anxious art dealers have been keeping a low profile, and several wealthy collectors have been barred from leaving China while the investigation continues. Auction house giants like Sotheby’s and Christie’s have been asked to cooperate with the authorities in what has become a wide-ranging investigation.

“Lots of people here are not going into work, or they are only using junior staff at their offices and galleries,” said a Beijing gallery director who spoke on condition of anonymity because of the tension surrounding the issue. “They can’t arrest everybody, but everyone is still nervous.”

In the meantime Nils Jennrich and Lydia Chu, employees of the art-handling company Integrated Fine Art Solutions, languish in a Beijing jail on suspicion of smuggling, a crime normally associated with the illegal importation of drugs or arms. The charges carry a maximum of a life sentence.