. tonight on "nightline," manhunt. after a four-day arson streak terrorizes southern california, we go inside the tran tick search leading to the arrest of this man. tonight, the very latest on his story and his alleged motive. santorum's surge. with the crucial iowa caucuses less than 24 hour as way we're on the ground with rick santorum as he shocks the pundits and surges to the top of the pack. we'll take you there tonight. and au revoir, ketchup. why they think french fries are well enough alone and what else they're doing in the battle to keep kids slim and sophisticated.

good evening. i'm bill weir. the fires exploded one after the other. all over los angeles. more than 50 in 4 days and more than enough to worry a city already living with the constant threat of wildfires. but tonight according to police there has been a big break. a suspected serial arsonist is in custody thanks to the sharp eye of a volunteer sheriff's deputy. a man who virtually risks his life for a salary of $1 a year. here's abc's david wright with the very latest from l.a. >> reporter: more than 50 fires in 4 days. carports and garages from hollywood to the san fernando valley including a dozen new fires set just last night. so many arson fires that authorities weren't sure if they were dealing with one firebug or a series of copycats.

>> four days ago this task force didn't exist. four days ago, this series of crimes did not exist. >> reporter: the break this the case came early this morning from a rookie reserve sheriff's deputy sherr von lalizara in his fourth shift in a patrol car. >> as soon as i put on my lights and conducted the stop of the suspect i had an lapd vehicle behind me. >> reporter: he spotted a minivan on sunset boulevard with british columbia license plates matching a vehicle seen near some of the fire. >> it was close to the description provided by the task force as possibly being related to the recent fires. >> reporter: the grainy videotape from a security camera at one of the fire scenes showed a man in a pony tail. the suspect now identified as 24 harry burkhardt of hollywood has a ponytail too. >> you could see him.

he was already handcuffed. cow see his ponytail and everyone was like that's got to be him. everyone has been talking about a ponytail. >> reporter: rick savidge, a music producer in hollywood was so freaked out by the arson spree he downloaded a scanner app for his ipad to monitor developments. today he showed up at 3:00 a.m. just as police were bundling burkhardt into the car. one of many interested bystanders. >> because obviously everyone in l.a. hates this guy right now. so, you know, some of these kids were kind of throwing him the finger. he's got this big smile on his face like he's the joker. oh, this guy is insane and obviously he is. he seemed like a character from a batman movie. >> reporter: authorities say a search of the minivan uncovered flammable materials that match what started the fires. but perhaps the biggest clue that authorities got the right man, the arsons suddenly stopped. >> we have not responded to any fires since this individual was detained this morning just after 3:00. >> reporter: veteran arson

investigator thomas derby has helped solve dozens of these cases. how unusual is it to have a spree of arsons like this, 55 arsons in 3 or 4 days? >> this is the most i've ever seen. >> reporter: you've been following it with interest. >> yes. >> reporter: do you think it's one guy? >> normally in an arson suspect like this it is one person. pyros usually set fires by themselves. they don't want a lot of people watching them. they get a thrill out of knowing that they caused this problem. >> reporter: he says often serial arsonists will stay close to the scene of the crime. is it likely when the person set this fire that they hung around somewhere and watched? >> a lot of times they are in the area. because they want to see what happens. >> reporter: but what could possibly lead someone to cause all this damage and endanger total strangers? >> just isn't fair. it's not right and it's not fair and whatever his personal issues are, he shouldn't be taking them

out on innocent people. >> reporter: that's what vexes the victims of the hollywood arsonist. >> it's unbelievable. it's just some burnt up metal. >> reporter: and there are quite a few of them including roommates michael robbins and carol shandler. she lost her car. >> it feels like an act of terrorism that we're being targeted to spread fear throughout a community and in people's hearts. i just want to know what the reason is. >> reporter: sources directly involved in the case tell abc news the first thing burkhardt said he was taken into custody is "i hate america." he's a german national who authorities say may have been motivated by the fact that his mother is about to be deported. her deportation hearing took place in l.a. just before christmas. of course, that possible motivation doesn't explain everything. arson experts say there's often deeper pathology at work too. >> sometimes a sexual gratification, sometimes it's just empowerment. >> reporter: sexual gratification. >> yes, they get sexually

gratified by the power of the sometimes it's to control their habits. >> reporter: whatever may have motivated this arson spree, l.a. officials tonight communicated in no uncertain terms they take this very seriously. if. >> if you're considering committing a similar act of arson know that we will find you. we will arrest you and we will prosecute you to the fullest extent of the law. >> reporter: despite today's arrest, authorities are taking no chances continuing extra patrols and urging hollywood residents to keep the lights on in their carports just in case. i'm david wright for "nightline" in los angeles. our thanks to david. coming up next the latest from iowa on what some would call down and dirty politics and a late surge that could change everything for republicans. >> good morning, dave.

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well, for a lot of folks around the country it was the ball in times square that signaled our entry into a presidential election year but in iowa, they don't need a ball. they've had campaign ads, ad naush shum in recent weeks but in a few hours all the jockeying will give way to actual votes. mitt romney is neck and neck with ron paul but rick santorum has rocketed into the hunt and my co-an authorize terry moran is in iowa with all of it. terry? >> reporter: bill, the republican race here in iowa has been an absolute roller coaster with conservative voters falling in and out of love with every candidate. everyone that is except for mitt romney and tonight while romney leads in the polls the man of the moment is rick santorum.

he is basically moved -- spent a lot of time here and in the final hours of this campaign it is finally paying off for him. we joined him on the trail today. what a difference a week makes. >> rick. >> reporter: just a few days ago he couldn't buy media coverage and could walk into his events unmolested. today we tried to talk to him to take the pulse of his surging campaign, look ahead to the coming contest and got into a crazed media scrum. senator, do you think you have the organizational legs to go forward? people say you've spent all your time here -- >> i've been in south carolina more than any other candidate in the campaign. i've been second according to "the washington post" in the amount of time i spent in new hampshire. we feel good. we have a good team in all those places and if we can take it from here. >> reporter: santorum's rise came the hard way. >> happy fourth of july. >> reporter: months and months of work on the ground meeting voters in more than 370 town meetings in every one of iowa's 99 counties.

and for months and months, it got him nowhere. >> rick santorum of pennsylvania. >> reporter: you could see it in the debates where he was almost an after thought way, way off to the side and just before christmas -- >> i saw him as a champion for the family. >> reporter: got a couple of key endorsements from influential pastor, years of taking a hard line on social issues like abortion and gay marriage paid off. and the former senator from pennsylvania who got creamed in his last campaign caught fire here. when did you know this campaign was taking off? >> you know, we felt the crowds were getting bigger and things were happening. we felt good for the last couple of weeks. >> reporter: so santorum's surge is perfectly timed but is he just the latest flavor of the month? >> 9-9-9 plan. >> thank you, i do want you to be with me. thank you. >> reporter: republicans here have made just about everyone in the race a front-runner at some

point in their apparent quest to find anyone but mitt romney. today romney boldly declared they failed. >> we're going to win this thing. >> reporter: his crowds are big and growing. he's got a ton of money and he's been running here for years as we saw firsthand tonight. he ought to do well. >> please welcome ron paul. >> reporter: but the passion it seem, the fervor is elsewhere. ron paul has lit up many young people and disaffected voters with his ideologically pure libertarian message. >> we accepted the idea that the federal government's responsibility was to intervene in the economy. >> reporter: at paul's iowa headquarters it seemed i was the oldest person there. >> everybody around him is young. why? >> i believe we're going to be the first generation who probably won't do as well as our parents and dr. paul is the only candidate who offers us something different. >> freedom is a very young idea. >> reporter: we caught up with paul tonight and he seemed a little nonplussed by his rock

star status. you know, one thing that's really striking is in your crowds are young people. coming out in droves and lit up. >> i haven't figured it out yet. i believe that young people are more open to consistency and principle. i think all of us like that. i think all young people whether you're a toddler or a teenager like independence. >> reporter: he's as pure as they come and that led some to wonder if he is a serious candidate for president or a kind of libertarian prophet out to shake the system, not govern it. when you lay your head down on the pillow at night do you see yourself in the oval office? >> not really. but i think it's a possibility. sometimes i kid about it. i says that's the risk i take, you know. >> reporter: and amazing admission from a presidential candidate. and not one you'd hear from santorum. and now come the attacks on santorum. now that's doing so well,

including this shockingly cruel comment from liberal pundit alan colmes describing inaccurately how santorum and his wife grieved their dead newborn child in 1996. >> by taking his two-hour-old baby who died right after childbirth and played with it for a cull of hours so his other children would know that the child was real. >> reporter: this afternoon at a town hall in newton, santorum was asked about that. >> we got together and we brought gabriel home with us to bury him. >> reporter: nearby his wife karen wept. those values have gone straight to the heart of what socially conservative iowans care about, lynn roger got on the santorum train early back in october. what was it like to be a santorum supporter for all those months when he was at like 1%, 2% in the polls? >> it was tough to see him that low. i wanted -- i wanted the media -- i wanted to call the media and say you're missing it. you're missing it.

you're missing out. you got to speak with him. go see him because when you see him, you change your mind. but it was hard, but i felt good in my heart. >> reporter: but whether iowa conservatives will vote their hearts tomorrow or with the man many think has the best chance to beat barack obama, that is the question here tonight. >> terry, thanks to you and we'll know a lot more in 24 hours from right now in a special edition of "nightline." your voice, your vote. the iowa caucus edition. join us if you can. coming up next, why the french are so worried about ketchup. ♪

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french women don't get fat was the title of a best-selling diet book but an envy instilling title doesn't seem to apply to french children. like the u.s. they are dealing with the childhood obesity problem but they're taking step is its to restrict mayonnaise and voted to place a special tax on soda and as jeffrey kofman tells us the french food police are after the most american of condiments. ♪ >> reporter: it is impossible to imagine paris without the eiffel tower. or the french without their gourmet food. it's almost a religion and these days this is, well, almost the

anti-christ. yep, ketchup is such a big threat to the french culinary tradition that they've all by banned it in the country's schools. middle school in suburban paris is typical. virtually all french kids eat lunch at school and we are not talking burgers and fries. on the very adult menu here today, fresh fruit natures, selection of cheeses and veal with lentils or baked fish with peas so i'm looking around and i don't see any ketchup. where is the ketchup? there is no ketchup says this school nutritionist. >> why not ketchup? these foods don't need ketchup. if i gave you some ketchup, would you have ketchup with that? at the risk of corrupting france's future leaders we put the ban to test. >> i take it. ♪ >> reporter: watch the ketchup criminal's face carefully. he knows it's wrong but he can't resist. >> reporter: why do you like

ketchup? "it has a lot of taste," he says. of course, just like in the u.s., the ban on unhealthy food is in property a concern about child obesity. why ketchup? well, it has a lot of salt and sugar known to make us fat. you can understand why the french are getting a little paranoid about their food. there are more than a thousand mcdonald's restaurants in this country or mcdolt's as they call it here and this has been in recent years the most profitable place in the world outside of the united states and they come with ketchup, a lot of ketchup. this in a country where irate farmers tore apart a mcdonald's a dozen years ago. >> we go to the supermarket here and there's an aisle of ketchup. obviously somebody is eating it. >> reporter: american food writer david leibovitz lives in paris. he says it's easy to see why the french have taken aim at ketchup. >> because ketchup is a really

good target. it's a way to say, oh, here's something that is making our kids fat. it's american. it's a processed product. it's something that comes in plastic bottles. >> reporter: in saying we're going to limit ketchup in the schools, what are they trying to achieve? >> i think they're t preserve a way of eating that is in danger of getting lost. ♪ >> reporter: here in france ketchup can a victim of what might be called a culinary crusade. in schools here they don't just teach science and history but the difference between gourmet and glutton. i'm jeffrey kofman for "nightline" in paris. >> our thanks to ketchup pusher jeffrey kofman there. voters in iowa will begin to shape the presidential race tomorrow and "nightline" will have a special edition with the latest results, and analysis. until then thank you for watching abc news. "gma" in the morning, "jimmy kimmel" coming up next. always online at abcnews.com.