The body of John was put in a tomb (Mk 6:29-6:29)

“When John’s disciples

Heard about it,

They came.

They took his body.

They laid it

In a tomb.”

 

καὶ ἀκούσαντες οἱ μαθηταὶ αὐτοῦ ἦλθαν καὶ ἦραν τὸ πτῶμα αὐτοῦ καὶ ἔθηκαν αὐτὸ ἐν μνημείῳ.

 

This is similar to Matthew, chapter 14:12.  Mark said that John’s disciples heard about this incident (καὶ ἀκούσαντες οἱ μαθηταὶ αὐτοῦ).  They came (ἦλθαν) and took his body (καὶ ἦραν τὸ πτῶμα αὐτοῦ).  They buried the body of John the Baptist in a tomb (καὶ ἔθαψαν αὐτὸ ἐν μνημείῳ), but there is no indication of where they buried John’s body.  Here, they did not go and tell Jesus about this, like in Matthew.