Novel about aliens retrieving human hybrids pre-birth

Question

I read this book back in the early 90s. I think the cover had a pale tan/peach color background, with two people on the cover, both with eyes that were glowing, or at least solid white.

It was called something like "The Perseus Factor". I only remember some snippets from it:

• I think one of the main characters was a detective hired to investigate a disappearance.
• There are two aliens, and at one point they have sex, but instead of touching, they lay on opposite sides of a bed/table/device, and touch a projection of the other above them.
• Someone, I think one of the aliens gets killed in a fight. I remember a snippet of dialog about the light going out of their eyes, and I think it was literal light, being aliens and all.
• The aliens had implanted alien hybrids into human women, and they were retrieving them. They always refer to them as zygotes.
• At the end, a message gets sent to the alien homeworld/mothership/something, and the ending dialog says that it'll take ten years for the message to be received, and another ten for the aliens to arrive.

Answer 1

The Perseus Breed, a 1988 novel by Kevin Egan.

His first novel, The Perseus Breed, combined a science fiction story-line with strong mystery genre elements. In the book, Borley Share’s obsessive quest to understand the sudden disappearance of his first serious girlfriend uncovers the existence of an alien race using the Earth as a nursery to raise its young.