London, Mar 21 : Austrian incest fiend Josef Fritzl has spent the first night of his life sentence in jail with a cellmate who is on suicide watch amid fears for his mental health.

Fritzl was found guilty for locking up and raping his daughter in a cellar over 24 years, fathering seven children with her and causing the death of his own infant son.

At the start of the four-day trial, Fritzl pleaded not guilty for the boy's murder and imprisonment, however, after the testimony of his daughter Elisabeth, he changed his plea to guilty on all counts of the indictment.

According to officials, the 74-year-old won't be left in a single cell, at least for the near future, reports Sky News.

Fritzl''s next stop will be Austria''s top secure mental institution for sex offenders.

He could spend up to six months at the Mittersteig prison hospital in Vienna, where he will have access to facilities including television and newspapers.

From there, Fritzl will join a cellmate in either Graz, Garsten or Stein.

However, he is likely to be on suicide watch for the rest of his life behind bars. (ANI)