San Diego police released a sketch of the serial killer responsible for a string of violent attacks on homeless people. — San Diego Police Department

A 12-day police manhunt for a serial killer targeting homeless men across San Diego came to a dramatic end Friday when a pair of officers in Golden Hill came across a fifth victim, who was screaming in pain, and an hour later a police dragnet snared a suspect.

Suspect in homeless killing of three men and injury to two others is detained at Laurel and Horton early Friday morning... San Diego News Video — San Diego News Video

The latest victim, a 55-year-old man who was sleeping near an Interstate 5 overpass at C Street, is expected to survive, police said.

San Diego police arrested Jon David Guerrero, 39, about three miles away on Laurel Street near Union Street, police Capt. David Nisleit said at an afternoon press conference. Guerrero faces three counts of murder, two counts of attempted murder and two counts of arson.

Court records show a history of arrests and mental competency hearings, including one judge's order that sent Guerrero to Patton State Hospital for psychiatric treatment.

Both Nisleit and police Chief Shelley Zimmerman, also present at the news conference, stressed that they are confident Guerrero is the serial killer police have been looking for.

"I firmly believe, and want everyone to know, I am firmly confident Guerrero is the suspect," Zimmerman said.

"There is no doubt in my mind, this is part of our series," Nisleit said Friday morning.

Nisleit, who has headed a massive investigation since the first victim was slain, then set on fire on July 3, said detectives found physical evidence at the scene of the Friday attack and in a search of Guerrero's downtown San Diego residence that "definitively links" Guerrero to the killings.

"We have the right person in jail," he said.

Police had arrested a different man, Anthony Padgett, last week, noting he had a 2010 conviction for setting a homeless man on fire. He also resembled a suspect in the current series whose image was caught on a Bay Park convenience store surveillance video. Padgett was released from jail on Monday with investigators saying they had exculpatory evidence that excluded him as a suspect.

Nisleit said a large number of officers around the city have been on the lookout for the killer, and officers scouring neighborhoods around the latest attack found Guerrero across the central part of the city, on Laurel Street near Interstate 5. The man strongly resembles the suspect from the surveillance video and a police sketch.

"This is just good police work, is what it appears to be ... having a lot of officers available in a quick minute (to) flood an area, looking at all possible avenues of escape," Nisleit said.

About 4:30 a.m. Friday, two Harbor Police officers who were headed toward their station were passing through Golden Hill when they heard a man screaming, Nisleit said. The two found a homeless man at 19th and C streets, bleeding from a severe chest wound. San Diego police were notified.

"The victim, all he can tell us is that he was asleep and was awakened when he was attacked," Nisleit said.

Investigators quickly determined that the attack fit the pattern in the serial killings, in which men sleeping alone suffered major upper body chest wounds. Police have not disclosed what type of weapon has been used, and Nisleit did not say whether a weapon was found near the latest victim. Two of the five victims were set on fire after being wounded.

CSI and San Diego Police Department homicide at the scene Friday where a fifth homeless man was attacked in downtown San Diego. — John Gibbins

Officers cordoned off the area of the latest assault. Evidence technicians photographed a cardboard box and pillow where the victim had lain. Other officers, searching for evidence, walked along B Street, a possible route the attacker used to get from C Street to Laurel Street, where the arrest was made.

Guerrero was detained wearing a green, Greek fisherman-style hat backwards, a gray sweatshirt over a plaid hoodie, long shorts, athletic shoes, white socks and black gloves. He was riding a bicycle and carried a backpack that held a hammer.

An officer recognized the cyclist as the suspect from photos, which clearly showed his green hat, and the police sketch that depicted his large chin, big ears and prominent eyes, Nisleit said.

Michael McConnell, an advocacy worker for the homeless, said he was having breakfast near Golden Hill when he heard about the attack, and he saw the roped-off crime scene. "It's going to be a huge relief for the homeless," McConnell added. "(Police) certainly weren't going to stop until they got him. This is certainly particularly heinous. What would drive a person to do this?"

The captain said Guerrero grew up in Coronado , but he didn't know if the suspect had ever been homeless or knew the attack victims.

Public records show an extensive history of criminal cases in San Diego, dating from 1999 to 2009, and several mental health cases filed in 2008, 2009 and 2011.

Guerrero was arrested in 2007 and pleaded guilty the next year to charges of burglary, grand theft and possession of marijuana and narcotics paraphernalia. His mother, Kathleen Guerrero, wrote a number of letters to the court on her son's behalf, seeking psychiatric treatment for him in jail.

She explained why he didn't do well on probation, saying he had trouble following directions or keeping track of time and appointments. In one letter she pointed to “David’s lack of hearing and speaking ability. In the past a symptom of his illness has been to insert foreign objects into his body orifices and I am concerned that this may be the case again.”

He was arrested again in 2009 and pleaded guilty to robbery for repeatedly knocking down a homeless woman and stealing her bicycle. Again placed on probation, he violated the conditions and was ruled not mentally competent. He spent time at Patton State Hospital. His attorney, arguing for a lesser sentence, wrote that Guerrero "begins to hear 'good' and 'bad' voices" when his medication wears off, but that on the appropriate medication he "can lead a normal, productive and crime free life."

In earlier cases from 1999 to 2001, he was convicted of burglary, grand theft and possession of stolen goods

A Facebook page for a Jon Guerrero shows he went to Coronado High School and worked as a caregiver for a time. One posting said he was from Cuernavaca, Mexico. Other postings are rambling, including one 2015 statement that said, "There something to do with the stars in the sky and the gate way to your soul. I think it's the cotten I was wearing. . Well Vicky it's hood to know there's still some love in me or innocents s .. but I can really see the mix of my mom & dad in me what was God thinking?"

ATTACKS ON HOMELESS

The first attack in the series occurred about 8 a.m. on July 3 in Bay Park, where the body of Angelo De Nardo was found off Morena Boulevard, near railroad tracks. He had been killed, then set on fire. Video of the man believed to be the killer was caught at a nearby gas station convenience store, and the clerk who sold the man a gas can assisted police in creating a sketch of the suspect on Wednesday. That sketch was widely circulated on Thursday.

Contacted at the store Friday, the clerk said he didn't want to possibly harm the investigation by comment about how the sketch may have helped break the case. He said police had not been back in touch with him since the arrest.

On July 4, about 4:50 a.m., Manuel Nunez Mason, 61, was critically injured on Greenwood Street in the Midway District. Less than two hours later, Shawn Mitchell Longley, 41, was found dead of injuries on Bacon Street in Ocean Beach.

Then, about 5 a.m. on July 6, witnesses heard loud pounding noises and saw one man in a gray hoodie set another man on fire in a grassy spot along a walkway between condominium complexes off State Street and Kettner Boulevard, south of Broadway in downtown San Diego. Investigators said a towel was ignited on top of the critically wounded man, 23-year-old Dionicio Derek Vahidy. A witness grabbed away the towel before the victim was burned. Vahidy died of his injuries Sunday.

As the investigation into the attacks intensified, the FBI was asked to create a profile of the serial killer. That work was still in progress as of Thursday, Nisleit said.

Adding to confusion about the slaying series, police identified a separate series in which a man riding a bicycle has struck homeless men on the head, generally around downtown and East Village. There have been more than a dozen such attacks in the past few weeks. Another apparently occurred on Friday in the Bankers Hill area, reported about 4 a.m., half an hour before the victim was discovered in the slaying series.

At the Friday news conference, Mayor Kevin Faulconer praised police for the arrest of "a disturbed murderer."

"We said all resources would be brought to bear to catch the person suspected in a string of brutal murders and attacks on San Diegans struggling with homelessness — and they were," the mayor said.

City Councilman Todd Gloria issued a statement saying in part, “With today’s arrest, I am hopeful that these senseless and cowardly attacks on some of our city’s most vulnerable neighbors will now come to a definitive end.”

Gloria added that, "we must continue to push for increased permanent supportive housing options throughout our city that will get these individuals off the streets and into safety."

McConnell said he is in touch with other homeless advocates around the country and finds that violence against the homeless is generally on the rise.

"How much of it is driven by the negative perception we have toward these people?" McConnell asked. "How do you gauge that?"

He said he believes the homeless are reporting violence more often now in San Diego because of the severity of the assaults. They don't often bother reporting less vicious attacks such as being kicked or having objects thrown at them, he said.

"It will be satisfying to see that someone doing this (serial killings) is off the streets," McConnell added. "But it won't surprise me if we see more of this."

View the Video Violence against the homeless