The Dallas police department has now upgraded charges against Brown to capitol murder, citing forensic evidence that links Brown to the child at the time of his death.

This comes as no surprise to anyone researching the case, since Dallas police announced two weeks ago they would be charging him with murder.

My first guess as to what that evidence might be would be Cash's blood found on some article of Browns clothing.

The problem with that reasoning is that since Brown was at the Sherrod house after the killing and this is already known to everyone, that evidence could have easily been planted on or got on him then.

At any rate this is no surprise really, keep in mind this is the same police department that murdered a witness whose testimony convicted Dallas police officer Amber Guyer of murder and DPD has a long history of corruption and institutionalized racism.
This it is also why the FBI is investigating the DPD and this case itself. There is obviously a power play going on between federal authorities and Texas state authorities, probably rooted in Ken Paxton.