Daniel Pelka trial: Mother accused of starving her four-year son before beating him to death Magdalena Luczak, 27, and partner Mariusz Krezolek, 33, deny murder Daniel Pelka was so skinny he resembled 'concentration camp victim' Boy's biological father Eryk Pelka says he often found Luczak drunk Couple 'would often argue and she'd lash out by hitting him over face' Mr Pelka 'broke up with her after she cheated on him with his friend' Investigator says boy's hair had fallen out when he inspected his skull Trial: Magdalena Luczak (pictured), of Coventry, is accused of depriving Daniel Pelka of food A mother accused of starving her four-year-old son before beating him to death was an aggressive drunk who threatened the boy's father with a knife, a court heard today. Magdalena Luczak, 27, and her partner Mariusz Krezolek, 33, of Coventry, are accused of depriving Daniel Pelka, of food, force-feeding him salt and locking him in a home-made prison. The toddler was so skinny he resembled a "concentration camp victim" before he died from a head injury in March 2012, Birmingham Crown Court was told. Daniel's biological father Eryk Pelka said he regularly found Luczak drunk while looking after their son, and the pair would regularly argue - with her lashing out by hitting him over the face. He told the court she once threatened to stab him with a knife at a party, and he had to call the police. They met in Poland in 2004 then moved to Coventry a year later before Daniel was born. But their relationship deteriorated and he eventually left Britain to return to his native Poland when Daniel was aged one. Mr Pelka said he had "fierce arguments" with Luczak. Speaking through a translator, he said: "They are only my thoughts but she was aggressive towards me. She was shouting and calling me names and she was trying to hit me as well. Mr Pelka said at a party in 2007 police had to be called after Luczak threatened him with a knife. He said: "We were at the party together and we had been drinking together. We were arguing all the time and she grabbed a knife. I rang the police and the police came and arrested both of us because I was drunk as well. I was pushing her away. Mr Pelka said Luczak would "repeatedly" slap him across the face. He said on two occasions he had to call into work and pretend to be sick because Luczak had not come home from a night out. He also said he came home late from his job as a lorry driver on at least two occasions and found her drunk. He said: "She was drunk and Daniel was lying on his own and no-one was looking after him." The pair moved to Coventry in 2005 and shared various addresses before and after Daniel was born in December 2007. Hearings: A file sketch of Magdelena Luczak (right) and Mariusz Krezolek (left) at Birmingham Crown Court Police were called to several domestic incidents involving the couple - sometimes by Mr Pelka and sometimes by Luczak. Mr Pelka denied ever being violent towards his ex-partner. Daniel, who was so badly starved he weighed just 1.5st - 15lbs below average - was found by horrified paramedics with a head injury on March 3 last year. Earlier in the trial the court heard his levels of emaciation were like those seen in parts of Africa and his Body Mass Index was too low to even register on the scale. Despite being rushed to University Hospital Coventry doctors were unable to resuscitate him and he was pronounced dead. Mr Pelka told the jury when he left England to return to Poland, Daniel was "really chubby." He said: "He was as all normal children are, he was healthy, he was not neglected. Even his granny said that taking into consideration he had been drinking English milk, he's really chubby. Toddler death: Daniel Pelka was so skinny he resembled a 'concentration camp victim' before he died The jury also heard from Grzegorz Lukasik, a former colleague of Krezolek at an automotive factory in Coventry. He said Krezolek had described Daniel as 'autistic' and said he did not respond to beatings because of his mental condition. At the trial: Eryk Pelka, biological father to Daniel Pelka, leaves Birmingham Crown Court after giving evidence today He said: "I remember he said that he [Daniel] had autism and it's not even worth beating him because he won't feel any pain because he's autistic. I have never heard any good words about Daniel. Meanwhile the court also heard that Mr Pelka broke up with the boy's mother after she cheated on him with one of his friends. He said that he and Luczak's relationship had deteriorated after she found a new partner - who had been living with the couple at the time. He said: "I was sick and tired of the arguments and the cheating. I found out Magdalena had cheated on me with on of my mates. When I left our relationship was not very good, Magdalena already had a new partner. Their relationship started just before I left England but I can't remember exactly when it was. I got up once and went upstairs and Magdalena just told me about it. He lived with us at the time. Mr Lukasik, who worked with Krezolek, said Daniel's stepfather had spoken of sending the youngster 'back to Poland'. He said: "He mentioned they would like to send him to his biological father but because there's a very strong bond between Magdalena and Daniel it probably won't happen." Lead investigator Detective Inspector Chris Hanson, of West Midlands Police, said when he examined Daniel's body on a mortuary slab the little boy's body was in a "wretched state." DI Hanson, who has investigated 80 child deaths over 21 years, said the schoolboy's hair fell out when he inspected the corpse. He said: "I was pretty shocked actually, I would describe him as grotesquely thin. His body was in a completely wretched state and I was completely shocked at the severity of his emaciation. His appearance was akin to a child from famine-affected Africa. He was very pale. Even wearing plastic gloves I could feel that his hair was very frail and brittle. DI Hanson said Daniel's hair had fallen out when he inspected his skull. He said: "I could also see to the back of his head there was a swelling. I felt the injury and I instantly suspected it was a subdural [brain] bleed. It was obvious to me Daniel had been murdered. Krezolek and Luczak have admitted child cruelty, but deny charges of murder and causing or allowing Daniel's death.