'I lashed out at someone who didn't deserve it': San Antonio man says he killed unsuspecting cop because he was 'upset' by a custody battle - and now he wants to apologize to the slain man's family

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'Upset': Otis Tyrone McKane, 31, said Monday his shooting of San Antonio detective Benjamin Marconi on Sunday was because he was 'upset' about a child custody battle

The gunman arrested for murdering a San Antonio cop 'execution-style' outside a police HQ claims he did so because he was 'upset' by a custody battle, it emerged Monday.

Otis Tyrone McKane, 31, told police that he 'lashed out at somebody who didn't deserve it' when he shot Detective Benjamin Marconi, 50.

Speaking to press on his way to Bexar County Jail in San Antonio late Monday, he said: 'I've been through several custody battles, and I was upset at the situation I was in, and I lashed out at someone who didn't deserve it.'

He also said he wanted to apologize to the family of the slain detective. 

Marconi, a father of two, was shot through the passenger side of his patrol car Sunday, mySA reported.

McKane was arrested without incident after a SWAT team pulled him over on Interstate 10 East near Ackerman Road, East Bexar County, at around 4.20pm. A woman and a child were also in the vehicle. 

Apologetic: Otis Tyrone McKane, 31, was arrested Monday in the fatal shooting of a San Antonio cop. Investigators say he targeted the law enforcement officer 

McKane that that he was 'sorry' as he was taken away by police. He is accused of shooting a cop who was writing out a traffic ticket at close-range 

Detective Benjamin Marconi, a 20-year department veteran and father of two, was sitting behind the wheel of his vehicle at around 11.45am Sunday when a man pulled up behind him, shot him twice in the head, and fled. 

Police had earlier released a photo and video of a suspect entering the police station around four hours before the shooting, and promised $10,000 reward for info.

It's believed that McKane was that same man, San Antonio Police Department told DailyMail.com.

McKane had previously been jailed for 60 days in 2012 after pleading no contest to a misdemeanor charge of assault with bodily injury of a family member, mySA said.

Marconi was writing a traffic ticket in his car outside police headquarters on Sunday, when the suspect pulled up behind him in a black sedan near West Nueva Street and Santa Rosa Street. 

Marconi, a father of two, was writing a traffic ticket in his car outside police headquarters on Sunday when he was shot twice in the head

Police had released a photo of a man they are looking for in connection with the shooting of Marconi, but it's yet not clear if this is McKane

Marconi was writing out a traffic ticket when he was shot dead in his squad car by a driver who pulled up from behind (pictured: police at the scene on Sunday)

The suspect got out, walked up to the patrol car's passenger window and shot Marconi in the head, according to San Antonio Police Chief William McManus.

The man then reached into the window and shot him a second time in the head before he got back in his car and fled the scene.

Marconi, who had been on the force for 20 years, died in the San Antonio Military Medical Center at about 12.30pm. 

McManus said earlier Monday: 'I feel we were targeted. I think the uniform was the target and the first person who happened along was the person he targeted.'

The San Antonio police department released a photograph of a man they say 'might have information on the murder' as well as images of a black Mitsubishi Galant with custom rims. That man is believed to be McKane.

The suspect was described as a black male with a goatee, and believed to be 20-30 years of age. He is between 5'7" and 6' tall, with a possible tattoo on his left arm.

A video was also released by the police, showing the suspect lingering outside the police headquarters before walking into the building.

He spoke to an officer at the desk, who offered to help, before turning around and exiting. Marconi was shot around four hours later.

However, it remains unclear why he was there.  

Police questioned one man but let him go, the police chief said Monday, adding that it was still unclear whether the suspect lived in San Antonio.  

Investigators reviewed dashcam video, but McManus declined to say what was captured in the footage.   

Texas Governor Greg Abbott released a statement extending his condolences to Marconi's family, and said he would sign legislation that would make targeted attacks against law enforcement a hate crime.   

'This is everyone's worst nightmare, the officers in the department, the family and everyone who supports the officers,' McManus said. 

'Our hearts go out to all of Detective Marconi's family, to all our SAPD brothers and sisters for whom this has hit home hard.

'Most families will be celebrating the holidays, SAPD will be burying one of its own because of an ultimate act of cowardice by a suspect who will be caught and brought to justice.'

The Marconi family called the detective a 'peace officer' in a statement on Monday that also thanked people for 'the outpouring of support, prayers and love'.

Meanwhile, McManus has advised officers in the department to pair up for their safety. 

Prior to the attest, the suspect was described as a black male with a goatee, aged 20-30. He is between 5'7" and 6' tall  (police are also looking for this car with custom rims)

Marconi was just one of four cops across the country who were shot on Sunday. 

In a separate incident, a St Louis police sergeant was hospitalized in critical condition after he was shot twice in the face around 7.30pm on Sunday.

The 46-year-old officer was sitting in traffic with his window down and said he thought the other car was pulling alongside him to ask a question. 

The suspect opened fire instead and was later shot dead trying to flee from the police.  

St Louis Nayor Francis Slay said: 'He was targeted because he was a police officer. He didn't deserve this. It looks like he's going to survive. He's going to be OK. 

'But this is traumatic. It's traumatic for him, his family. It's traumatic for the city of St. Louis. He was just doing his job.'

Four cops were shot in separate incidents on Sunday. Police officers were injured in San Antonio Texas, Gladstone and St Louis Missouri, and Sanibel, Florida

Two more officers were shot on Sunday.

A cop in Gladstone Missouri, pulled a vehicle over for a traffic violation on Sunday night before the suspect bolted on foot.

Police officers tried to arrest the suspect, who displayed a handgun during the struggle, according to the Kansas City Police Department. 

The Gladstone officer was shot and taken to the hospital with non-life threatening injuries, while the suspect was fatally wounded. 

In Sanibel, Florida, a police officer was sitting in his patrol car finishing a routine traffic stop when he was hit by a drive-by shooter.

The suspect was taken into custody and the injured officer has already been released from the hospital. 

ABC13 captured police blocking off the street where an officer was shot dead on Sunday

San Antonio Police Chief William McManus (pictured) said the suspect got out and walked up to the patrol car's passenger window and shot the officer in the head

Chief McManus described the shooting in San Antonio as a targeted killing similar to recent shootings in Dallas, Texas and Baton Rouge, Louisiana.

A gunman killed five officers in Dallas who were working a protest about the fatal police shootings of black men in Minnesota and Louisiana. It was the deadliest day for American law enforcement since Sept. 11, 2001.

Ten days after the Dallas attack, a man wearing a ski mask and armed with two rifles and a pistol killed three officers near a gas station and convenience store in Baton Rouge, Louisiana. 

'It's always difficult especially in this day and age where police are being targeted across the county,' McManus said.

'Unfortunately like Dallas, like Baton Rouge it's happened here.'

San Antonio Mayor Ivy R. Taylor said: 'I want to extend my deepest condolences to the family of the officer killed outside police headquarters today as well as to our entire police force.

'This type of crime cannot and will not be tolerated.'