  The heaviest neutron stars and lightest black holes expected to be produced
by stellar evolution leave the mass-range $2.2$ M$_{\odot}\lesssim m \lesssim
5$ M$_\odot$ largely unpopulated. Objects found in this so-called lower mass
gap likely originate from a distinct astrophysical process. Such an object,
with mass $2.6$ M$_\odot$ was recently detected in the binary merger GW190814
through gravitational waves by LIGO/Virgo. Here we show that black holes in the
mass gap are naturally assembled through mergers and accretion in AGN disks,
and can subsequently participate in additional mergers. We compute the
properties of AGN-assisted mergers involving neutron stars and black holes,
accounting for accretion. We find that mergers in which one of the objects is
in the lower mass gap represent up to $4$% of AGN-assisted mergers detectable
by LIGO/Virgo. The lighter object of GW190814, with mass $2.6$ M$_\odot$, could
have grown in an AGN disk through accretion. We find that the unexpectedly high
total mass of 3.4 M$_\odot$ observed in the neutron star merger GW190425 may
also be due to accretion in an AGN disk.
