The court temporarily adjourned yesterday morning after the double-amputee runner started to sob while testifying about the moments before he killed Ms Steenkamp in his home on February 14, last year.
Chief prosecutor Gerrie Nel had asked him what he shouted as he moved towards the bathroom where he shot Ms Steenkamp, who was behind a closed door in the toilet cubicle.
Pistorius said he thought there was an intruder in the house. After a long pause after the question, he said he screamed, using an expletive, for the purported intruder to get out of his house. As he gave evidence, Pistorius began to wail and Judge Thokozile Masipa called an adjournment. Just over an hour later and after court resumed, Pistorius again broke down when replying to a question on why he had opened fire, causing a second adjournment.
The prosecution has said Pistorius's account of a mistaken shooting is a lie. Mr Nel opened the fourth day of cross-examination by alleging that Pistorius had "concocted" his account of the shooting.
"You're tailoring your version as you're sitting there," Mr Nel said.
Mr Nel alleged that Ms Steenkamp was in the process of getting dressed in the midst of the night-time argument and wanted to leave shortly before the shooting. A pair of jeans strewn on the bedroom floor showed Ms Steenkamp was putting them on, Mr Nel said, and contrasted with her character as a neat person who would not leave clothes lying around.
Pistorius, who denies murder, responded that Ms Steenkamp was neat, but he said the jeans were inside out and therefore showed that Ms Steenkamp had not been in the process of donning them.
The case, in Pretoria, South Africa, continues.