What happened to Tyrek Lannister?

Okay, so in ACOK the riot of King’s Landing takes place, and in the riot a number of men are killed, among those are Ser Aron Santagar, Ser Preston Greenfield and the High Septon. During the riot the son of Tygett Lannister and Darlessa Marbrand, Tyrek Lannister goes missing. Later on in ASOS, Addam Marbrand is made Commander of the Goldcloaks and continues the search for Tyrek or his body but has no luck. So where could Tyrek be? Fast forward to AFFC and Jaime Lannister suspects that Varys had a part in the disappearance of Tyrek. Tyrek could be useful for Varys because Tyrek served as a squire to Robert Baratheon alongside his cousin Lancel. This means that he would have certain knowledge about Robert and the circumstances surrounding his death, having spent so much time around him. The knowledge of this would be valuable to Varys. Furthermore Varys does not go down to the docks to see Myrcella off to Dorne this could be because he was organising the Kidnapping of Tyrek. Lastly, in an interview from 1999 GRRM is asked if we will ever find out what happened to Tyrek and Martin replies ‘Yes, you will. I try not to leave too many loose ends. But sometimes you need to wait.’ As this was in 1999, GRRM could have changed his plans of Tyrek.