"20/20" INVESTIGATION: SCANDAL INSIDE THE PEACE CORPS - ARE THEY PUTTING WOMEN IN DANGEROUS SITUATIONS AND PUTTING THE CORPS' REPUTATION AHEAD OF THE SAFETY OF ITS VOLUNTEERS? BRIAN ROSS' EXCLUSIVE REPORT AIRS ON "20/20," FRIDAY, JANUARY 14

Also: Elizabeth Vargas Interviews Ron Reagan, Jr. on the Centennial Anniversary of the Birth of His Father, President Ronald Reagan;

And: Monkeys Who Drink Give New Meaning to "Party Animals" - How Alike are They to Humans?

The Peace Corps is one of the most iconic and respected organizations in the world. Started by President John F. Kennedy, its very name embodies the best ideals of service -- to help people. But on the eve of its 50th anniversary, has it put young women volunteers in dangerous situations -- and then told them to keep quiet about it, all to protect its reputation? ABC News Chief Investigative Correspondent Brian Ross' exclusive investigation into this and the murder of young Peace Corps volunteer airs on "20/20," FRIDAY, JANUARY 14 (10:00-11:00 p.m., ET) on the ABC Television Network.

Kate Puzey was a beloved Peace Corps volunteer in the African country of Benin when she was murdered. Her family and the people in the village where she served still ask, why would anyone want to kill Kate? The "20/20" investigation uncovers a scandal within the Peace Corps involving Kate's attempt to blow the whistle on a Peace Corps employee she suspected of abusing seventh-grade girls.

In the second part of the investigation, Ross reports that more than 1,000 female Peace Corps volunteers have been raped or sexually assaulted in the last decade. As with the Puzey family, some of the victims say the Peace Corps has sought to cover up the incidents and treated the victims with insensitivity, more concerned with the agency's image than the volunteers' health. Peace Corps officials tell "20/20" the agency has a commitment to the safety of its volunteers.

Video preview: http://abcnews.go.com/Blotter/video/peace-corp-volunteer-nightmare-12582789

Story preview: http://abcnews.go.com/Blotter/peace-corps-gang-rape-volunteer-jess-smochek-us/story?id=12599341

Also: On the centennial anniversary of President Ronald Reagan's birth, Elizabeth Vargas interviews son Ron Reagan, Jr. about his notoriously conflicted relationship with his father, whom he describes as "easy to love but hard to know." Ron speaks candidly about lifelong ideological disagreements with his father, his parents legendary love affair, the persistent rumors about his own sexuality, watching his father decline into Alzheimer's and eventual death, President Reagan's conservative legacy and the current Republicans whom would like to appropriate it.

Preview: http://abcnews.go.com/Politics/ronalds-reagans-sides-son-writes-memoir-mark100th/story?id=12584957

Plus: ABC News Correspondent John Berman reports a story that gives an all-new meaning to "monkeying around"� Vervet monkeys are giving tourists and natives a run for their money in the

vacation paradise of St. Kitts in the Caribbean. The monkeys raid local outdoor bars and steal rum cocktails, beer, soda, and fruit drinks from unsuspecting tourists dozing on their beach chairs. Those who drink too much alcohol seem to stagger and stumble around afterward, similar to drunk human behavior. These monkeys have learned to be sneaky and opportunistic, and they are very bold -sometimes timing their visits to �happy hour' or even going straight to the bartender for a drink. But it's not all fun and games. Instead, researchers are discovering a lot about human drinking habits... by studying these drunk monkeys.

"20/20" is anchored by Elizabeth Vargas and Chris Cuomo. David Sloan is executive producer.