The 42-year-old actress left the series to give birth to her first child with husband Peter Hermann after the ongoing eighth season's premiere episode -- her character went deep undercover in an eco-terrorist group, Zap2it.com reported.
With her maternity leave over and her character's undercover work completed, the Emmy Award-winning actress will rejoin the cast in Tuesday's episode of the popular crime drama, the report said.
The Web site said it is unclear how long actress Connie Nielsen, who has served as a replacement on the series for the last four episodes, will remain with the NBC show, as she still has two episodes remaining on her initial contract.
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