and heads to iowa. saying he's got a plan to bring back the jobs. really. abc's jake tapper catches up with him. good evening. i'm cynthia mcfadden. we begin tonight with what increasingly appears to be a murder investigation. it's playing out on the caribbean island of aruba. tomorrow, it will be two weeks since robin gardner, a 25-year-old woman, disappeared after traveling to the island with a man she met online. his troublesome past is coming to light. here's abc's matt gutman. >> reporter: arubins again find their tiny sun-swept island the setting of another possible murder mystery. with gary, at first blush, a bereaved boyfriend, who claimed his travel companion had gone missing while snorkeling, now led out of a police station in disgrace. the only suspect in the disappearance of 35-year-old bin gardner. this evening, prosecutors ordered him held for another 16 days. here in aruba's kia prison, that's nearly twice as long as they originally pushed for. >> yes, it's not yet at the moment to declare -- >> reporter: investigators suspect foul play in robin's disappearan disappearance. friends say the 35-year-old from maryland just wanted to get away after having recently lost her job. >> when she came to me and said, hey, i'm going to aruba, i was, like, cool, so happy, get out of town, why wouldn't you. then she said she was going with gary and it just became a why. like, why, you know, are you sure. >> reporter: christina jones said she was wary of who her friend was leaving with. >> well, i know that she met gary over a year ago online. it's been a real roller coaster frieship. it's pretty hot and cold. one day nice and the next day not so nice. >> reporter: authorities now know she landed here on july 31st and planned to stay a week and she was last seen on or near this rocky beach on august 2nd and that there was a critical time gap between the time when giodarno claimed he last saw her and when she reported her missing. prosecutors tell "nightline" their decision to detain him is based on his record, especially these documents, restraining orders against him, fileded by o maryland women and obtained by abc news. in one of them, a petitioner says he started to choke me with both hands and shovedis fingers down my throat. there were other women who found his behavior alarmingly aggressive, including his ex-wife. who said local police were involved in one incident. and then there's carrie emerson. she tells abc news he called her after seeing her teenaged daughter's photos on a website. >> he said he was a producer and he had an opening for one girl to go to aruba to shoot with him. he said it's not going to be another natalee holloway or anything. >> reporter: holloway is the alabama teen who also went missing on this island in 2005, nener to be found again. now, carrie emerson had never met giordano. >> he started tolding me if i went and i slept with him, he would make sure i was taken care of financially. he said, if you let your daughter sleep with me also, i will take care of both of you financially. told him he was nod interested. he cursed me and i hung up on him. >> reporter: she says she reported the incident to the fbi which has been assisting the arubins, even raiding his maryland home, confiscating everything from laptops toell phones. >> there's no proof and there's no motive. >> reporter: while the portrait of this man has come into focus, robin guaardner's last few days and hours remain a mystery. abc news has learned this is where robin gardner was last seen. a dive shop and restaurant. its owner wouldn't go on camera but described exclusively to abc news what happened. he says robin and giordadao ate but didn't drink here for about an hour the afternoon she vanished. they went into the dive shop but didn't rent gear. the dive shop owner told us he saw them out here in this dirt road that's in a remote partt o the beach. he was surprised to see anybody snorkeling out here because it's so rarely frequented by anybody in a mask and fins. giodarno claimed they came down to this beach to snorkel. an unusually calm day. water flat. it's here that the trail goes cold. arubin authorities were criticized for being caught flat-footed in the holloway disappearance in '05 so they've been tight-lipped about this case. can we just ask you one question? just for one second? but prosecutors here are still miles away from a conviction. they may have their man in custody but they have no body, no murder weapon and still no answer to the question of what happened to robin gardner. for "nightline," matt gutman, aruba. >> it is a case we will continue to follow closely. just ahead, how a bad break-up could have a silver lining. 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man 1: only if he's ready to rock! ♪ sfx: guitar and trumpet jam vo: geico. 15 minutes could save you 15% or more on car insurance. with vitamins and minerals balanced to support your energy... ♪ ...and healthy skin. everyday benefits from advanced formulas. discover the complete benefits of centrum. well, diamonds are forever, even when the relationship isn't. after a painful break-up, the sentimental value of jewelry that was given as a gift may be ruined, but that does not mean the jewelry still isn't valuable to somebody. that's where the auction websites we're about to introduce you to come in. they take heartbreak and turn it into consolation cash. here's abc's andrea canning. >> reporter: for some women, it's the best gift they'll ever receive. >> ashley, will you marry me? >> yes. >> reporter: the moment of truth on "the bachelorette." and the moment of squealing joy in the summer blockbuster "bridesmaids." >> i'm engaged! >> oh, my god! >> reporter: the beginning of a journey that will last the rest of their lives. or at least one hopes so. >> this is my engagement ring and my wedding ring. >> reporter: how do you feel when you look at that? >> you know, sad. >> reporter: for this woman, her wedding ring brings back bittersweet memories. >> it's a symbol i took seriously. i told him i was ready to start a family. he had wanted kids. yet at that moment, he said, you know, i don't have any interest in that. >> reporter: so they divorced soon after. and then -- got engaged again? >> yeah, it turned out it wasn't so much of a real engagement. >> reporter: she was left at the altar with little explanation. >> he canceled the morning of. so it was very, very, very painful experience. >> reporter: but she's not alone with her broken heart. and now a new cathartic and lucrative trend is emerging. break-up jewelry auctions. in the first "sex and the city" vie, the ladies head to ogle jewels at a break-up auction. forget about the old pawnshop. everyday women are selling those rings online to the highest bidder. websites like idonowidon't.com are popping up. at ex-boyfriend jewelry.com, users can sell, trade or give away their memories for $1.99 per listing. but there is one condition. sellers must accompany the sale with a story. one scorned seller, for example, wrote, gorgeous engagement ring i got in the divorce. apparently my ex-husband would rather be with his secretary than his loving wife. >> it's a really nice sense of closure. when you're ready to post something on the site. we get a few of the people where it's still raw. >> reporter: megan started the site with her stepmother marie when she was looking to unload some of her own ex jewelry. >> i had a wedding set. i'd been married very young. woops. and to go to apawnshop, that seemed really --icy. >> reporter: within day, the site had so much traffic it crashed. since then, one engagement ring has sold for $2$2000. with gold selling at record highs, there's never been a better time to unload that old hardware. do you get a lot of angry women? >> we notice after big holidays like in january there's a lot of, he gave me this thing for christmas and next thing, you know, i find out he's having this affair. >> always be aware of heart-shaped jewelry. one of our mottos now is 1 in every 10 relationships ends in heart-shaped jewelry. >> reporter: how off season jewelry fought after? >> in divorce, they find things to fight over. when you add to that items that are of extreme value, it's a perfect storm. jewelry representss money. i have never had a female client say, i love this piece, i got to have it, i want to keep it. it's completely changeable to cash. where as the pet is not, grandma's portrait is not. >> reporter: it works for celebrities. jennifer lopez's 6 carat diamond ring was reacquired and auctioned off. remember ellen barkin's very public purging of her divorce jewels? she raked in millions at a christie's auction. >> will you marry me? >> yes, yes. >> reporter: "bachelor" star jake pavelka and vienna endured a public engagement with this beautiful ring. then an even more publicized break-up. >> please stop interrupting me! >> reporter: the ring went back to the production company and the exes are now opening up on abc's "bachelor pad." >> we booth looked like fools, you know, in front of america. >> i accepted jake's apology. people need to really start focusing on the present. >> reporter: today, meimei fox is doing just that. are you going to get married again? >> i think so, yeah, i believe so. >> reporter: no proposal yet though? >> nope, nope, it's been discussed. but i'll leave it at that. i believe that i'm with the love of my life truly. >> reporter: so, along with her rings that she's selling on exboyfriendjewelry.com for a total of nearly $7,700 -- >> prepared to last as long as thee memory will. >> reporter: it's also out with her old wedding dress which is now going for nearly $1,000. how do you think you're going to feel when this sells? >> you know, i really feel like it's a cathartic process. unloading some of the emotions. >> reporter: she plans to donate some of the money to charity. hoping some of her bad memories will turn into good karma for someone else. for "nightline," i'm andrea canning in los angeles. >> fascinating. one question remains, if you break up, should you give the expensive stuff back? let us know what you think. just ahead, the president is in iowa. home base these days for a gaggle of republican politicians who would very much like his job. vegas! now?! 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[ female announcer ] we all go. why not enjoy it a little more with charmin ultra strong? and to help feel fresh and clean, try charmin freshmates. the president today kicked off a three-day bus tour through minnesota, iowa and illinois, hoping to recapture the magic that sent him to the white house. won't be easy. polls put his approval rating at an all-time low of 39%. the white house insisted hee wa not campaigning but, rather, was just, quote, doing what presidents do. here's abc's senior white house correspondent jake tapper for our series "the contenders." >> reporter: in front of this gorgeous tableau of americana this evening, a barn, a flag, a stretch of rusted iowa, president obama outlined a major campaign strategy. after congress returns after labor day. >> i'll be putting forward when they come back in september a very specific plan to boost the economy, to create jobs and to control our deficit. and my attitude is get it done. and if they don't get it done, then we'll be running against a congress that's not doing anything for the american people and the choice will be very stark and will be very clear. >> reporter: he's no longer the fresh-faced junior senator who electrified iowa democrats more than three years ago. >> our time for change has come! >> reporter: but that doesn't stop him from trying to recapture the magic. with that, campaign 2012 unofficially begins. heading into this first stage of the election, president obama faces a moment of crisis. coming off the bruising debt ceiling debate, the s&p downgrade and a roller coaster week for the stock market, the effects are showing. the president woke up today to the worst poll numbers of his administration. today, he tried to place the blame on the toxic environment in washington. the buck stops over there. > there is nothing wrong wit america that can't be fixed. ways broken is our politics. >> reporter: even though we're in iowa, just a couple days after the republican iowa straw poll, white house officials insist this is not a campaign trip. this is official presidential business. >> the midwest has always been a good place for democratic candidates, certainly it has been for the president in the last election. and, you know, just happens to be that there were republicans in iowa this weekend. i'm sure that had nothing to do with his decision to go to iowa. >> reporter: republicans have been getting thelion's share of attention lately. especially here in the midwest. over the weekend, the ames straw poll rejiggered the race, witit congresswoman michele bachmann claiming victory. contininng her meteoric rise to the top of the pack. and governor pawlenty dropping out of the race. >> coming to the state fair is pretty standard fare -- >> reporter: today, halfway across the state, the newest entry into the fray, texas governor rick perry, made an appearance at the state fair. a candidate for barely three day, the governor did not waste any time. >> go ask your veterans if they'd rather see somebody who's never served as the commander in chief. >> he engaged on mitt romney. he engaged on the president. so, seems as if he's coming out, late, but he's coming out strong. >> reporter: one thing all the republicans have in common, they're attacking the president on jobs. >> mr. president, you need to free up the employers of this country to create jobs. >> what we need, again, is a president who understands the economy. what we have to do. we have to lower the taxes on the job creators. why? so you can have more jobs. >> let me tell you what barack obama's doing. barack obama's killing this economy. barack obama is why 25 million people don't have jobs. >> -- only 17% of voters think the economy is getting better, there's going to be a lot more attention on who the president of the united states is going to be. we've had almost eight straight years of people believing that -- more people believing the country's on a wrong track than they think it's on the right track. so this is an electoratee that s hungry for some change, positive change, positive news. >> reporter: unless that happen, the president has got to change the focus from what he has not been able to do to what congress refuses to do.