“Dateline” had a successful return to two-hour episodes Friday night.

The two-hour murder mystery called “Twisted” won the night in Total Viewers averaging 6.02 million. The show grew with each half hour: 5.02 million at 9pm to 6.84 million by the 10:30 half hour.

“Dateline” topped its newsmagazine competion on ABC: A repeat of “What Would You Do?” at 9pm and “20/20″ (which included this story about a former Philadelphia meteorologist) at 10pm. It was a tie at 10pm in the A18-49 demo with “Dateline” and “20/20″ averaging a 1.5 rating.

This was the highest-rated Friday for NBC since April 20. “Datline” will be two hours on Friday nights until the Olympics begin July 27.