Viewers were able to vote on Twitter and CBS.com for the ending of this week’s “Hawaii Five-0.”

CBS is committed to experimenting on the Web when it comes to driving viewership and audience engagement, as evidenced Monday by a stunt that let fans decide the ending of a “Hawaii 5-0” episode. The Eye has a similar interactive promotion waiting in the wings for daytime gameshow “Let’s Make a Deal.”

During this week’s “Hawaii Five-0” episode, viewers were able to vote via Twitter and CBS.com on the ending — specifically as to which character would turn out to be a murderer. After votes were tallied throughout the episode, the winning ending was triggered. The East and West coast airings had separate live voting periods, and viewers in the two regions opted for different endings. (East Coast voted for #theBoss as the culprit, while West Coast viewers selected #theStudent.)

The volume of voting wasn’t off the charts, compared with online polling conducted by other shows, but network execs saw the effort as a learning experience. At a time when second-screen viewing is on the rise, the “Five-O” stunt was a highly promotable effort that encouraged live viewing of the show in its regular 10 p.m. slot.

“We were very excited about the results,” said Marc DeBevoise, exec veep and g.m. of entertainment, news and sports at CBS Interactive. “Social activity was up 186% according to our social guide numbers, and our site traffic to the show was up 200% from the average.”

Interactive programming has already been seen on CBS in live and semi-live alternative programming like “Big Brother,” where auds cancast their votes regarding elements of the “Big Brother” house.

“I love when we get to vote for what they eat on ‘Big Brother,'” quipped DeBevoise, adding that show is the one into which CBS has integrated interactive elements most frequently. “The ‘Hawaii Five-0’ episode was a way to take that to a dramatic, taped series,” he said. “It’s about getting people really invested in the programming.”

Some social media pundits did number-crunching on the “Five-0” interactive episode, and their figures showed that 7,200 votes were cast on Twitter during the East Coast broadcast, and just over 1,000 during the West Coast broadcast.

DeBevoise, however, told Variety that those Twitter numbers were “not entirely representative” of the voting. He estimated the “Five-0” votes to be well over 100,000.

While additional sponsorship was not integrated into the “Five-0” interactive episode, DeBevoise sees that being an element of future Web-driven initiatives.

“Five-0” exec producer Peter Lenkov is game to try the stunt again, even though it added to the workload of his production team.

“I liked the idea of getting viewers to watch the show live instead of DVRing,” he said. “It was an interesting way to tell stories and get the audience engaged. … By watching live, a show becomes water cooler conversation the next day. It makes for a better viewing experience.”

The “Let’s Make a Deal” stunt will invite Twitter users to vote for elements during the show’s taping on Jan. 25, for an episode that will air Jan. 30. The strategy may be harder to execute, since viewers will not be watching the show while voting, but instead will follow the action on “Deal’s” Twitter handle while the show tapes.