His lawyer Sakkie Maartens said Judge Chuma Cossie dismissed the application because she believed an appeal would have no prospects of success.
“I’ve already received instructions [and] I must proceed and petition to the Supreme Court of Appeal for leave to appeal to whichever court they see to be fit,” Maartens said.
In May, Cossie sentenced De Jager to life in jail for the “brutal and savage” murder of two teenagers.
She found no substantial and compelling circumstances allowing her to deviate from prescribed minimum sentences of life imprisonment.
He was convicted of killing and raping prostitute Hiltina Alexander, 18, in 2008 and killing Charmaine Mare, 16, last year. Both crimes were committed in Cape Town.
At the time, Cossie had agreed with Maartens that his client was not a serial killer as suggested by State witness Brigadier Gerard Labuschagne during sentencing arguments.
However, she said rape and murder were serious offences and needed to be punished in a way that would satisfy the interests of society.
“This kind of brutality is regrettably too a part of life in South Africa. Courts are expected to send out a clear message that such behaviour will be met with the full force and effect of the law,” she said.
“The legislature is concerned about this and so too should we be.”