Rodrigo "Digong" Duterte, the controversial politician known as the "punisher" due to his promises to kill criminals, is the presumptive winner of the Philippine presidency after an election day marred by chaos and violence.

Duterte has ridden a wave of discontent in the violence-stricken country to lead in opinion polls, on campaign promises to eradicate crime by shooting criminals, drowning them in Manila Bay or hanging them using fishing wire. He has a zero-tolerance stance on crime, and often boasts about turning the murder capital in the country, Davao City, where he has served several terms as mayor, into what is now touted as the most peaceful city in southeast Asia. He received frequent criticism from human rights groups for endorsing extrajudicial killings of alleged criminals by vigilante death squads.

He was also criticized last month for making jokes about an Australian missionary, Jacqueline Hamill, who was raped and had her throat slit in 1989 during a jail uprising in the Philippines' Davao City, where Duterte was mayor at the time.

Duterte, 71, told his audience that he was there when Hamill's body was brought out of the jail. "I looked at her face, and I thought: 'Son of a bitch – what a pity'" Duterte said. "They raped her, they all lined up."

"I was mad she was raped but she was so beautiful," Duterte added. "I thought, 'the mayor should have been first.'"

Election day was no exception to the violence that country is facing. On the eve of the elections, more than 135,000 officers of the Philippine National Police were deployed on election-related duties, and authorized to carry their assault rifles.

By dawn on election day, seven people had been shot dead in the town of Rosario, just outside Manila. As the day progressed, reports of incidents filtered in from across the Philippines. One person died when a grenade was launched into a market in the southern city of Cotabato. After delivering vote counting machines, a soldier was killed and another injured in an ambush involving a landmine and 30 armed communist rebels in the town of Gamay in northern Samar province. A voter was shot dead in a polling station in Maguindanao, and a local candidate was rescued Monday morning, a day after he was kidnapped by gunmen in the province of Leyte. One person died and two were injured after a shootout in Abra, a province notorious for election violence.

So far, a total of 25 people have been killed in related violence during the run-up to the elections and on election day. Police expect the numbers to go up as motives are determined for murders and crimes that occurred during the election season, and in the following 30 days. The numbers, however, are an improvement from the violence of past presidential elections. In 2010, 155 people were killed, including 57 people in a single massacre in the province of Maguindanao, 32 of whom were journalists.

Elections commissioner Rowena Guanzon downplayed the effects of the violence, saying that they would not impact the results of this year's elections.

But vote-buying likely had more of an effect on the outcomes of the more than 18,000 positions up for a vote Monday.

"Automated [elections] eliminated some forms of cheating but it increased the number of incidents of vote buying. It just blew up," Gregorio Larrazabal, former elections commissioner, told a local news outlet. "Vote buying now is just crazy."

Amounts varied from town to town, and ranged from 300 pesos ($6) to 5000 pesos ($105), depending on how hotly contested the race was. Residents of a town in Bohol reported being stopped by men on motorcycles who handed out 20 and 50 pesos bills on behalf of candidates.

Photos of hundred peso bills stapled to candidates names started popping up on Facebook, and people feeling flush with cash from election eve vote-buying, gathered in markets in the Philippines.

In the market town of Biñan, outside Manila, street seller Nyfa Sultan credits the festive atmosphere to election vote-buying.

"Yes of course, business is good right now," said Sultan, who was selling clothes and knock-off Birkenstocks, surrounded by bingo booths, market stalls and a rickety Ferris wheel. "All this is because people have some money from the elections. It's not right, but it does help people."

Sultan added that she hoped the best people win, despite the influence of cash.

At the polls, final attempts at swaying votes added to the chaos of the day. Unidentified men stole the ballots from a polling station in Basilan. Many poll watchers reported being threatened, including two in Marawi City who were ambushed and killed on May 9. There were reports of cheating, as well as long lines and complications in voting records that prevented voters from participating who believed themselves to be registered.

Nevertheless, Duterte maintained a solid lead in line with his survey numbers, as preliminary tallies started to come in on Monday afternoon. Despite accusing his opponents of "mass cheating" ahead of the elections, and his supporters threatening protests and riots should they feel their candidate was robbed of victory, Duterte said he was satisfied with the conduct of the elections. In a press conference in his home city of Davao, he offered unity to his rivals: "I would like to reach out my hands to my opponents. Let us begin the healing now."

Current President Benigno Aquino III, after calling Duterte a dictator-in-waiting, spearheaded a failed 11th hour attempt at unifying the other candidates against Duterte, but later offered to support the winning candidate.

Duterte will be inaugurated into office on June 30, 2016. He suggested he will begin in earnest, promising during his campaign to get rid of crime and corruption within three to six months of taking office. In his final rally before the election, Duterte reiterated his goals, "Forget the laws on human rights," he said. "If I make it to the presidential palace, I will do just what I did as mayor. You drug pushers, hold-up men and do-nothings, you better go out. Because... I'd kill you."